When your a ND (Neurodivergent) person, especially with ADHD it's really common to go 110% into something and then burn out.
Change takes time, with small baby steps. The body and mind signal alarm bells when there is a dramatic change in our behavior.
So if you are trying to reach any goal, physical, emotional, academic, social it's important to slowly ease or modify your behavior rather than jump fully in.
Examples: You want to learn a language but 30 minutes with Pimslur is too much to do everyday. Why not try a simpler course or app at just 15 minutes a day.
You want to lose weight: Instead of cutting 500 calories (which never works in the long run) try 200 calories. (Note calorie deficit is not the only way to lose weight, there are many other factors that could be important to look at and try)
You need to finish your degree but you keep dropping classes: Instead of doing 15 credits, try 12 or get an accommodations for 9 and take two classes in the summer
Slow and steady is not what ND folks usually want to hear, but just because our minds have sped up doesn't mean our bodies have, evolutionary speaking.
I strongly believe that because going too fast for so many years contributed to many years of chronic health problems later. No one can run on empty forever. Our bodies pay the consequences. The earlier a person can change the habit of doing too much then prevention of serious illness is possible.