DeanoD,

It's funny you mentioned working in Lumber Yard and lifting heavy things on a regular basis.
I worked commercial construction for 15 years, and even though I worked hard everyday ( we specialized in cement construction), I had ALL my back issues during that time!
Unlike a gym, often in the real world work environment, you can't always practice safe lifting/pulling practices. Your working on ladders/slopes/mud/ in confined areas. Sooner or later you hurt yourself, and often it stays with you for life.
 Mid 30's I got lucky and fell into a healthier lifestyle, which included daily exercise of some kind. My sore back eventually went away and I make sure it's not coming back.
 I'm a firm believer in being  PROACTIVE with my health and fitness, rather than RE-ACTIVE. It is a lot easier to stay in shape, than get in shape.  Couples that take care of themselves are much better at taking care of each other.
 There are "benefits" to being fit and healthy that have nothing to do with paddling  ;)
 Good Luck with your Health/Fitness plan. We'll EXPECT a trip report ;D