I've tried pretty much everything aside from prescription stimulants (can't get them)... The only things that work is some stuff I can get without prescription

I've tried pretty much everything aside from prescription stimulants (can't get them)... The only things that work is some stuff I can get without prescription (tolerance is a bitch, though) and exercise. Even after exercising, I feel good but I still can barely concentrate on anything, I have to always bring my attention back "manually", for lack of a better word.