Just change your  mindset, I know people who maybe 70, 80 or even  90 and still fitter and healthier then a 40 years old, you need take care of yourself physically and mentally but the most important don't make  life or the world about yourself we are just visitors for a very  limited moment of time,  we  needs to keep the place clean before leaving it  try to make the world a better place even better then you found it, just learn to Stop Worrying and Love life