Cycling did wonders for my mental health. It's something I can do solo but I also do it socially (I represent a local advocacy club). Being outside, feeling the wind, exploring your surrounding in a new light, etc. For working out, I believe than in the beginning it requires more discipline than motivation. Set yourself a goal, like riding/running/lifting/whatever for x amount of time (say 30min everyday o 2-3x a week) and just. do. it. Do it even if you don't feel like it, make a routine out of it to create anticipation. In time you'll notice that it gets less and less hard to get up and do the activity and then comes the movitation (like wanting to go farther, faster, lift heavier weights, etc).

If you're not feeling like going outside and since you mention wanting to make something, I'd recommend crochet or knitting. With crochet you can make amigurumi (stuffed toys) and with knitting you can make small items to gift (beanies, hats, cowls, scarves, etc). I recently discovered this craft myself and after noticing a positive effect I looked it up and turns out repetitive hand motions actually increase serotonine release. Plus the feeling of achievement after completing an item after some/lots of effort (and cursing) is very rewarding.