I highly recommend picking up a copy of Terry Laughlin
Triathlon Swimming Made Easy: The Total Immersion Way for Anyone to Master Open-Water Swimming
Do the drills, get in the mindset. My times are 20 seconds per hundred faster and I come out of the water with more energy
If I had to guess I'd say your problem is likely breathing. If you have the fitness from running and cycling, you should be able to do 400m no problem with ok technique. I went from a situation similar to yours to being able to swim a sprint tri comfortably in ~2 months. I found reading Total Immersion and doing a bunch of practice in the pool really helped. For whatever reason, reading about what I was supposed to be doing made it click more than any other teacher I'd had up to that point. I also did a workshop with the TI people, which really helped, but you probably don't have time for that.
I like this little book. It’s waterproof paper and you can take it with you. Kinda pricey, but still cheaper than the online plans.
Swim Workouts for Triathletes: Practical Workouts to Build Speed, Strength, and Endurance (Workouts in a Binder) https://www.amazon.com/dp/1934030759/ref=cm_sw_r_cp_api_i_NTYQSDSPV557GKDB0GWA
If you're a reading/visual learner, pick up Swim Smooth's book. It has taught me to get a solid freestyle stroke as a beginner after 20 sessions in the pool. Plenty of photos in there too to grasp a visual understanding of concepts.
If you don't savvy reading, consider getting some swimming lessons.
When I was doing Ironmans these workout flash cards were clutch. They’re organized by time and focus area (endurance, strength, distance, speedetc.) and they have some equipment options (paddles, flippers, board)
I tried to respond to your original post but I think you deleted it before it made it through. I'm a complete beginner swimmer, but I found the information in Total Immersion really helpful to bring me from feeling like I was swimming in molasses to swimming in water. The key is minimizing drag by getting your body horizontal and relaxed and balanced on your chest cavity.
Looking at the video, that will probably mean getting your head a little lower in the water and also changing up your stroke a little so that you always have one arm fully extended and down in front.
Again, take this with a grain of salt as you're already a significantly better swimmer than I am.
Have you read “Total Immersion“?
It sounds like you've got a nice relaxed stroke, and it may just be a matter of getting your body more horizontal in the water by finding a good balance point on your chest.
That being said, it also sounds like you're a more experienced swimmer than me, so take this with a grain of salt.
Usually I pull something out of this book:
https://www.amazon.com/Waterproof-Coach-Workout-Swimmers-Triathletes/dp/0965623009
Back when I swam distance, usually did a mile or two straight, but those days are loooonnngg since past.
McLeod's Swimming Anatomy is getting perhaps a little bit aged, but is a really good book. Comes with the exercises on DVD if you have a player for that. (I loaned the book once and the DVD got lost.)
Buy this book
This book has a bunch of different workouts:
I did some coaching while in Grad School (exercise science) and helped with their weight lifting program too. This book made it easier for the swimmers to understand the reasons why they were doing certain exercises (which goes along way for adherence and motivation)
https://smile.amazon.com/dp/0736075712/ref=cm_sw_r_cp_apa_fabc_YYOWFbRKQ34YG
Also, I got into designing swimming apparel as a side hobby, and sorry for the shameful plug, but you may like some of these ;)
For better head position, look forward a few feet, so that the top of your head is out of the water. Not so much that you're looking forward but just a few feet ahead of right beneath you.
Leg sinking is the biggest issue hurting your efficiency, it's basically drag, forcing you to put out much more effort than needed. I used to have the same issue, check out "Total Immersion Swimming" (https://www.amazon.com/Total-Immersion-Revolutionary-Better-Faster/dp/0743253434). Read through it and do the drills, after a month ro two you'll be far faster and more efficient in the water. You'll stop freaking out about being out of breathe as well.
As far as your kick goes, idk if there's a way to improve it, I have a shitty kick also. I'm a triathlete though, so I use a two beat kick (two kicks per stroke) to save my legs for the bike and run portions. This keeps me from exhausting myself and getting nothing for it.
Join a masters club, you wont regret it.
There is a person that has posted many masters workouts. Search "masters workout" for this sub.
I also recommend swim workouts for triathletes. I used this book until I joined a masters club. I have been snagging workouts from it, the person posting masters workouts, and some from masters coaches on my team during Covid.
https://www.amazon.com/Swim-Workouts-Triathletes-Practical-Endurance/dp/1934030759
If you live in Florida this is a must have book
https://www.amazon.com/Diving-Guide-Underwater-Florida-11th/dp/1878348396
It has not been updated in 15 years so it is missing some big iron like Vandenburg, Oraskani, and Lady Luck but still a really valuable resource.
Hey thought of one other thing. I swim with a team so I never use this anymore but this boom for Amazon was all I used for the first two years of swimming when I started triathlon. Swim Workouts For Triathletes
Right... just like people with wrong running stride get "runners knee", but if you use correct form it's not a problem. Swimmers shoulder is because so many people use wrong technique, putting stress on the joints/supporting tendons and ligaments. That's why tendinitis is also fairly common. Correct form will prevent that.
Also, your Dr. is likely not a swimmer and doesn't understand this, so of course he'll tell you to stop swimming. There is a great book called "fitness swimming" by Emmett Hines that breaks this all down. If you're interested in ever getting back in the pool, get the book and learn how to do it right so you don't risk re-injury. Swimming is just fine for your shoulders if you do it right, just like running is just fine for your knees if you do it right. The fact that so many people don't swim or run with correct form is the reason for their respective common injuries... not because those activities are bad for the shoulders/knees.
Link to the book: https://smile.amazon.com/Fitness-Swimming-Second-Emmett-Hines/dp/0736074570?sa-no-redirect=1
This video came from swim smooth and I really recommend the book.
Starting your swimming with this info helps you not make bad habits you'll have to break later!
I used to swim a long time ago, this helped me, instead of blindly swimming laps without any real plan. https://www.amazon.com/Waterproof-Coach-Workout-Swimmers-Triathletes/dp/0965623009/ref=sr_1_1?ie=UTF8&qid=1501298625&sr=8-1&keywords=waterproof+coach
Another good option: Swim Workouts for Triathletes: Practical Workouts to Build Speed, Strength, and Endurance (Workouts in a Binder) https://www.amazon.com/dp/1934030759/ref=cm_sw_r_cp_apa_ZNy6xbPRZRBBQ
Grab your self a book..
( This particular one is all free-style.. but you should get the point )
If you are a new swimmer, Swimming for Total Fitness is a great book and it has a plan and a variety of work-outs.
http://www.amazon.com/Swimming-Total-Fitness-Progressive-Aerobic/dp/0385468210
Swimming is probably more repetitive than you are used to, though. It is a skill sport. People who swim a lot do lots of repetition because the more you drill the skill, the more efficient the skill gets.
Technique technique technique. Read these books from cover to cover and work on your form every day:
I would get total immersion swimming for bettering your buoyancy.
If a person is doing a cardio routine say 4-6 times a week they shouldn't be going balls out each and every workout. If they swim like crap it's because they are fighting the water and swimming like crap which generally leads to a very high heart rate. Keeping your heart rate at a high level everyday you do cardio isn't best. With a little instruction and some time spent on technique swimming can easily become a regular part of a cardio routine for shitty swimmers. This book is pretty darn good for working on technique if you are a mediocre swimmer: http://www.amazon.com/Fitness-Swimming-Second-Emmett-Hines/dp/0736074570
I can highly recommend this book. It has training plans that slowly build. My recollection (it's been a while since I actually used the book) is that the plans start off ridiculously easy (things like treading water for X minutes) and progress through some serious, high intensity workouts. There is lots of focus on form. Lots of focus on non-full-stroke swimming (e.g., using a kickboard or using only one arm).
The Oriskany is a friggin Aircraft Carrier right off the coast of Pensacola in the Gulf! It was put down about 2 years ago, so it's not as pretty as it will be in a few more years, but it's the largest wreckdive in the world. Plus, there are plenty of places to spear-fish in the Pensacola bay area. If you want truly amazing dives in the gulf, you'll have to go down towards the Florida Keys. It's a haul but totally worth it, it's a divers dream. Plus along the way you can do a ton of freshwater cave dives if you're into that sort of thing. Florida has without a doubt the best dives in all of the U.S.. It can also boast the most Rec. Diving spots (per area/mile) in the entire world. I have been a Florida diver for 7 years and haven't even seen 1/10th of the dives yet. Check out this book more every dive spot (with GPS locations!) in FL, the best book I've ever purchased.
Decrap your swimming:
http://www.amazon.com/Total-Immersion-Revolutionary-Better-Faster/dp/0743253434/ref=sr_1_3
I went from being out of breath swimming the short way across the pool to doing laps without tiring in about 3 days after reading just the first chapter or two. It's definitely 95% doing it right and 5% endurance.
I've always been a decent swimmer, but I went ahead and joined a gym that has a swimming pool. I also started reading Total Immersion by Terry Laughlin, a 3 time Olympic coach. He breaks down the reasoning behind the techniques into simple layman terms. I'm still reading it, but I'm a much better swimmer already after only reading the first 6 chapters.
I bought the original Total Immersion book to learn how to swim better after I saw so many great reviews on it.
There is also a version geared toward Triathalons and open water swimming, here's an Amazon Link, you can get the original much cheaper if you order a used one.
The gist of the book is that swimming isn't about moving your arms as fast as possible, it is about being as streamlined as possible because the main thing that slows you down while swimming is drag. The fastest swimmers make it look so easy because they cut through the water like a hot knife through butter.
I would definitely recommend it, it has a series of drills where each builds on the technique learned in the last one. The book does a pretty good job of describing it...there is also a video you could obtain through legal or less than legal means.