@RightMeow
I'm not a psychiatrist and will be unintentionally giving you incorrect info in this post. You should go to a psychiatrist who will explain this to you correctly.
So you know dopamine? It's one of the reward drugs in the brain. It makes doing things feel good. If you have an executive function disorder like ADHD, you've got dopamine issues. Most of the time, with ADHD, your little dopamine brain factories aren't producing enough dopamine. So what you do doesn't feel rewarding like it does for other people.
When you're a kid, this manifests itself in the stereotypical ADHD ways. You aren't actually more energetic than other kids. It's just that sitting and reading quietly or figuring out a math problem is giving everyone else hits of dopamine, and you aren't getting any. So you do what does give you that hit. You fidget. You act out. You tend to do physical stuff. It gets you the dopamine reward other people get more easily.
For adults it's more complicated. No dopamine means no willingness to get out of bed in the morning. Maybe you procrastinate constantly. You need the anxiety of an impending deadline to kickstart your executive function (ADHD is an executive function disorder. So is OCD), because you don't have proper dopamine regulation.
And then, sometimes, you get explosions of dopamine. The factories go haywire. Burstfire reward hormones. The thing you're doing is so rewarding. It's the best thing ever. All that dopamine you haven't been getting is crashing into you like a tidal wave. Why would you ever want to stop doing this thing?
...ever heard of hyperfocus? Yeah. Burst fire mode.
So, ADHD drugs. What they do is to get the dopamine factories running smoothly. You get the same hits as everyone else. No more shortages. No more explosions. Just a steady flow like it's supposed to be.
How they do that is completely outside of my ability to explain, but generally it involves overclocking the factories a bit (this is why benzodiazepines are really bad for ADHD; they slow down the already malfunctioning dopamine creators). There are non-stimulant medicines on the market, but they're newer and less numerous.