Recently, I was diagnosed with hyperthyroidism. This, in short, speeds up everyday bodily processes, including heart rate and weight loss. Since Christmas, I've lost thirty pounds. Now, I've got loose skin that I'd like to tighten up. The issue is that my heart rate can be over 100 when I'm only sitting.

Are there any effective excersises I can do that will work for someone in my condition?

Have you had a complete medical checkup? Address the concerns of your heart rate with your medical doctor.