I'm nearing my 40s. In my mid-twenties I was diagnosed and over the next couple of years tried all of the usual ADHD meds and none of them were short of terrible in regard to side effects. I guess I've just learned to live with it in a way that outweighs the side effects I get from the drugs.
I was diagnosed with Shiftwork Disorder at one point in time and was prescribed Modafinil and it was incredible for the most part and had zero side-effects, but my doctor wont prescribe it for ADHD. One down-side to Modafinil is that I could get stuck on an unproductive task and would realize in hindsight that I had just been hyper-attentative to this unimportant task for hours.
Studies show Modafinil isn't effective in ADHD adults. It may have benefit in children with ADHD.
I think many prescribers give ADHD adults a high dose too soon causing side-effects. In my experience, it's best to start with a low dose and slowly increase as necessary. The myth is ADHD responds quickly, but observing hundreds of patients it takes months, not days, for benefit of treatment to develop. There's wisdom in the phrase, "start low and go slow".