I retired in September 2013 and fully thought I would devote my first non-working year to a "Magical Year of Gardening" - and that my beds would rival those in fine gardening magazines. Sadly, not so... Along with the aches and pains you note, I also found I am a fair weather gardener. If I start out working in the yard and then it starts raining, I will stay out until an actual downpour, but despite having adequate raingear, I rarely make the effort to begin gardening in inclement weather. Same goes for too much sunshine. Once the temps get too hot, I shut down and dive for the shade or the house. My ideal gardening weather is sunny/overcast and somewhere between 50-75 degrees. Although I've been trying to get all my beds fully winterized (last weeding, deadheading, mulching) that may or may not happen. I'm seriously considering hiring a lawn crew for spring cleanup, mainly to do the hard labor. But, a bit afraid of horror stories I've heard of crews digging up prized plants has put me off that a bit. And I've not priced it out, so that could well be another obstacle.
My goals for 2016 are (1) no new beds - always difficult since the vision is always so much more vibrant than the actual result, and (2) use the plants I already have (divide or move) or can trade for (i.e., no more big nursery runs).