I'm 16 years old, male, 6'3", 185 lbs. I have been prescribed Vyvanse to treat my ADD symptoms for about two years (currently at 70mg), and the results have been amazing. I have maintained a 4.0 GPA or higher in every grading period so far in my highschool career. But, I have recently noticed that I often get dizzy while doing cardio workouts, and a dangerously high heart rate. However, I'm in no means out of shape, and am extremely ripped. I'm worried that Vyvanse is messing with my heart, and I'm not sure what to do. I was a 3 sport varsity athlete as a freshman, and this issue is really giving me a scare. I would just stop taking Vyvanse, but it helps me do great in school, and I'm getting to the point where I'm dependent on the drug. When I don't take it for a day, i'm so tired that I can barely open my eyes, let alone function normally. I am always wanting more and more mgs, regardless of the fact that I know it's bad. Any suggestions? I need to solve this issue before it interferes with the bright future I have planned for myself. Thanks!