Sounds like you've tried exercise about twice in your life. Do it daily and you'll feel better.
It doesn't have to be the gym or a 45+ minute high intensity run - just jogging for 20 minutes and doing a few pushups or pullups is sufficient as „baseline activity“ for me.
If you are mostly sedentary, consume any form of what are toxins to a human (there's lot of kinds, don't get caught up on the buzzword), and then one day start working them all back out into your bloodstream at once, it makes sense to temporarily feel like garbage.