You should never use your thumb to take your pulse.
The answer is evaluating your present state of health. Best way to do that is to consult your doctor
and to see if you are fit enough for strenuous exercises. The next thing got a gym have the trainer
devise a plan to fit your health goals.
That way you will know the right type and amount of exercise you need to
be fit.
Death is a likely outcome to untreated bulimia.