[ThreeQuarter]

Lots of good advice above. I'm 45, so I can't say I know what what 50 feels like but I do know what it feels like to end the work week with nothing left in the tank, mentally. I feel a little guilty when I don't want to spend time doing the hobby I've already invested so much into. Among the good advice here that resonates with my experience, I'd have echo 67ChevyRedneck's advice about diet and exercise. My wife helped me see what cutting out sugar can do--overall it makes me more energetic and clear-headed and only my taste buds miss it. It has also helped me to do *something* every day/weekend even it's just sweeping or straightening up. These small habits have a way of building into something bigger over time.

All that being said, I also find it's not productive to push too hard to MAKE myself work on the project. I don't want to resent the green machine--the whole idea is for this hobby to be rewarding--so I wait until I have some motivation. If you have a job that flogs you some weeks, don't let guilt get you down if you need to take a weekend off from the hobby. If it's your hobby, it should be a rewarding challenge, not an obligation.