Great article for those of us that are older

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Being “Useful” means so many things to me now. It means much more than just another rep or a new PR. Now I understand better that to be useful is to be ABLE to enjoy my life to its fullest.
LIFE MATTERS. The effort that I put into my training, diet and active mobility will directly affect the quality of the life that I am afforded the luxury of living.

http://www.tabatatimes.com/5-laws-for-masters-athletes/