I turn half a century next year and have really only been cycling for about three years of focused work. I’ve kinda come to the realization that, at best, I would be a mid-packer in my age group if I wanted to race, so I’m focused on watts because that aligns with my goals for 2019 - a few centuries that are relatively flat for my area with some hills.
Like you, I have been focusing a little more on building lean muscle mass (nothing crazy) that aligns with my goals over the past several months and I find that I feel ‘better’ overall and I know it has improved my cycling. My diet has also improved since I’ve been focused on cycling by making better choices (not buying the Swedish Fish and selecting fruits) but that’s not to say I don’t enjoy a treat now and again.