I am on some of the same meds as you. Lithium can cause people to gain weight, although I did not.
Abilify is supposed to be weight neutral, but I don't believe that ANY antipsychotics are weight neutral.
They all fvck up metabolism.

Someone told me to focus on eating protein to keep weight off AND to help improve the Vyvanse.

I try to exercise 3-5 times a week, nothing major because I hate it. I usually walk/jog or do a workout tape.
Exercise is supposed to be good for the mind too, so my pdoc and T recommend it. I just find it boring.

Watch how much you eat out. Nothing is healthy, even if it says it is. Stop eating fast food/take out and watch what you drink.
I used to eat out all the time, then I got broke and stopped. I dropped some weight just by doing that.

Go see a nutrionist. I went and thought it was a really good education about food and weight gain/lose.
I actually learned stuff and they can take into account the foods you like, your meds, etc.
You health insurance might cover it.