This looks like an interesting course that I thought you guys might be interested in. It doesn't start until September but you can register now.
EDIT: It looks like the post was removed from UnresolvedMysteries for whatever reason. Here is the link to the course: FutureLearn.
It is on online class about using forensics to identify human remains.
You just have to get down and do it. Even if you don't think you're any good. Especially if you don't think you're any good, because you're not going to get good if you don't practice.
Start small. A single scene, a simple action-reaction sequence, a character introduction, something like that. 100 words, 200 words, that sort of length. Maybe think up a few prompts, some based on your own experieces or observations of things going on around you, to have a go at. Here are a suggestions that might give you a starting point:
A character goes to a shop to buy a specific item, that is only sold in that shop. It's sold out. What do they do?
A character realises they have gone a week without crying, for the first time in a while. What are their thoughts about this?
A character sees a friend in a location the friend shouldn't be. Does your protagonist confront their friend? Why is the friend there? How do the two characters act?
Your character trips over their own feet in a moment of clumsiness, and causes significant damage to something nearby that belongs to someone else. What do they do?
Also have a look online for prompts, exercises, challenges and courses that might help you get things moving. There's currently a course on FutureLearn called Start Writing Fiction, that just started and is on week 2 right now, that you might find helpful.
FutureLearn has some courses about mental health and psychology that are free to do - you can find them by browsing in the health and psychology section.
I enjoyed this one: https://www.futurelearn.com/courses/mental-health-and-well-being and I’ve also signed up to do https://www.futurelearn.com/courses/beyond-diagnosis