 [ Symptoms ] im 314lbs and trying to lose weight i cant excercise 2 min before im gasping for air how can i get a work out in [ Disease ] based on your age your target heart rate would be between 82bpm and 114 bpm this is based solely on your age if you want to calculate this based on your fitness level you can use the karvonen formula target heart rate = max hr   resting hr × intensity + resting hr take your pulse at rest subtract this from max hr 220 minus your age multiply this by 60 and 70 to get your target heart rate range