By "bad knees" what do you mean? Does your knee just hurt like its wore out or does it dislocate or sublux? Subluxation is a partial dislocation and a lot of people have subluxing knee caps during physical activity. The knee cap will move slightly to the side of the knee when you twist hard, very pain full and causes lots of swelling.

If its subluxing or dislocation get arch supports for your shoes and then a brace like this

[link]

Wear a knee brace. https://www.amazon.com/Knee-Brace-Stabilizers-Patella-Support/dp/B07F9W9BHX/ref=sr_1_5?dchild=1&keywords=Knee+brace&qid=1604298365&sr=8-5

going to buy this, unless someone has a better idea.

Knee Brace with Side Stabilizers & Patella Gel Pads for Knee Support

https://www.amazon.com/Knee-Brace-Stabilizers-Patella-Support/dp/B07F9W9BHX/ref=pd_sim_200_10?_encoding=UTF8&pd_rd_i=B07F9W9BHX&pd_rd_r=425df908-e21e-4953-bb31-4bbea37a6ef4&pd_rd_w=YU8z2&pd_rd_wg=STVn5&pf_rd_p=64e5d61b-7067-445e-bd1c-f84491d96b7e&pf_rd_r=KFKFWD0TTZX644F7F98G&psc=1&refRID=KFKFWD0TTZX644F7F98G

I bought one off of amazon (primarily for running, but use it here too) and it works well.

I'm assuming you're male, so this one would work well—https://www.amazon.ca/Knee-Brace-Stabilizers-Patella-Support/dp/B07F9W9BHX/ref=sr_1_8?keywords=knee+brace&qid=1584232291&sr=8-8. I bought it (female) and it's a bit too big for me).

Has velcro though, so it's great to be adjusted! Also don't hesitate to mod stuff to make it less jump-y. I do all the time. OR, mod things to help stabalizers around your knee. For ex, in Hollywood today, instead of the balance trainer jump on squats, I stood on it and did squats.