aging = rate of damage / rate of repair Some damage is intrinsic, caused by free radicals, wrongly transcribed DNA, misfolded proteins etc. Some damage is cau

aging = rate of damage / rate of repair Some damage is intrinsic, caused by free radicals, wrongly transcribed DNA, misfolded proteins etc. Some damage is caused by external factors like sunlight (skin damage), sugar, smoking, pollution, radiation etc. Things that increases damage increases aging and things that decreases rate of repair also increases aging. Exercise increases rate of repair and slows aging in that way, while sitting still all day decreases the rate of repair and thus increases aging. You seem to think that aging is only the intrinsic damage, but in many cases the type of damage that happens can be the same and external factors can increase the intrinsic damage that happens continuously. Some of this damage will decrease cellular repair mechanisms and thus decrease the rate of repair and you get a vicious cycle, external damage like having a hand chopped of doesn't really influence cellular repair, but smoking and sugar intake do influence cellular repair in a negative way and can thus be said to accelerate aging.