Why does vyvanse (lisdexamfetamine) 70mg make me feel lazy and unmotivated? what shold i do?

Could be side effect: Two possibilities come to mind: 1) perhaps, compared to your energy level off stimulants, you "feel" different and interpret that as lazyness; or, 2) it may be a genuine side effect, because some people do report a "zombie" effect with stimulants. In either case, might try a lower dose and see if you can get benefit without that feeling. Or, try a different adhd medication.