We all have a wonderful mind that takes an extremely beautiful and complex world and lets us interact with it. Too many people believe that the interaction is not on their terms - they react, hope for the best, let other events or people control them, and play the victim. I hope that you choose the opposite.
With so much going on in this world of billions and the constant information overload presented to us our brain creates filters to keep us sane. Through action or inaction we pick the filters. The very easy example of this is when you buy a new graphite black/grey Toyota 4Runner and then suddenly you see other Toyota 4Runners everywhere. You never noticed them before but it now seems like they are everywhere you look. You have changed your filter and are now paying attention to this information that was always there. Want to be happy - look for confirming evidence. The secret is that is was always there. Want to feel like your body is young and new? Act like it. With every bite of food be thankful and ponder on how this meal will make you grow, bring you health, repair you, and let you operate in health and pleasure. When you take a fall while on the mountain consider how well you feel after it, how your body just did an amazing thing absorbing many times your body weight without breaking. Focus on warmth and healing knowing that any tightness, bruising, or pain is your body already on the job of not bringing you back to where you were but making you even stronger so that next time it wont hurt. You are consciously changing your filter from one of negative to positive. Change your filter and give it a positive emotion as well.
I kinda threw int there the positive emotion thing without much explanation. The emotion is one of the biggest components to this filter. It will not be easy. My articles are short and the application is long. You will fall. You will get discouraged. You will allow your old filter and old emotion to take over. That is fine. Notice your filter, notice when you did not select it properly and then grow. Filters are the key to happiness.