Not to be taken lightly

A casual friend that I spend time with up at the hawk watch,  retired 4 years ago at the age of 51. He made a remark that really made me think.  He said that when it came time to make his decision as when to retire he asked himself if he would enjoy the ages of 50-60 more then 60-70.  He decided that he loved hiking and doing outdoor sports  far more then having more money and the chance that at 60 he will no longer be able to get out there like he does now.  WOW double WOW!  How very true is this?