This trial will test the effects of two different types of exercise on people with anxiety disorders and high anxiety sensitivity. The first group will do low intensity exercise while the second group will do high intensity exercise. The trial will use heart rate as an objective mechanistic target for exercise intensity, examine changes in valuation of exercise through a neuroeconomics task, examine changes in interoceptive sensitivity with a heartbeat detection task, and integrate of ecological momentary assessment (EMA) to measure effects of immediate changes in mood with exercise on anxiety outcomes and adherence.