In practice, ADHD is what you have when stimulants make you get better.

If your laundry lists of symptoms (depression, sleep disorders, lack of motivation etc) get better from stimulants, count yourself lucky. Stimulants work right away, if they work at all, and have few and relatively mild side-effects.

Some of the side-effects, like weight loss, are even seen as welcome by many people. Others like having to pee more often and cold hands are relatively easy to deal with.

For comparison, antidepressants take months to show even mild positive effects; and have major side-effects.