https://www.reddit.com/r/cyberpunkgame/comments/kamwa2/athletics_skill_not_levelling/

I've found out that by hitting a wall with your fists and depleting stamina let's you level up your stamina skill.

same for me. I'm stuck at level 1 with 62 out 500 needed for next level. I then tried the trick of punching the wall mentioned above... that worked.

i tried a few other things and it seems from what i can tell that athletics only goes up if stamina is totally depleted -- draining down half way or so doesn't seem to advance it. I was able to get it to go up by doing the following:
1. punchwall until it is depleted
2. punch air -- turns out i didn't have to punch anything, just had to keep swinging until depleted stamina.
3. use melee weapon (baseball bat type thing)

all of the above gave me points after about 3 times of depleting completely.