Age 33. Male. Caucasian. Immediate tiredness from any sort of exercise. This has been the same all my life. I played sports and took part in senior level, pre-season training for 3 months. I did not miss a session. Yet, I would go to zero energy, quickly. At the end of the 3 months I was not any fitter. zero energy is the closest I can describe any physical exertion or stressful(My Dad would frown from even uttering that word.) I feel weak. History of fainting(3 times) but not for over a decade(No standing for long periods of time) When I was 5, I was sent to the Children s Hospital to check a heart murmour. The Doctor said I was Strong as an Ox. Zero flexibility in the legs. I add this, because an unrelated internet search led to stiff arteries as a possible cause of the poor flexibility. I have little body fat and would be considered slim. At the moment, I stay away from any cardio and completely cut out caffeine of any form. Is there anything I should do or take, short of going to my local MD?