Self improvement is tiring

I now have 3 months of successfully running 3 miles 3 mornings a week completed. Completely coincidently now that the 4th month of the year is starting, I'm going to increase to 4 mornings a week. With the improvement in the weather I'm taking the dogs walking/hiking in the evenings more. I'm eating healthier--many days at lunch I wonder why I always run out of spinach in my salad, despite the laughably tall pile falling off my plate. Of course, I usually put something interesting (like a lean cuisine pizza or the meat/cheese of a turkey sandwich) on top of it. I'm dancing more, camping, and gardening again. During the week I keep up pretty well with everything. But lately on the weekends I've just crashed. I still do stuff, but I feel so dragged out I end up laying around reading for hours. It's like all the motivation and will power I have during the week evaporates for those 2 days. The problem is that it comes as a shock, I feel like I want to do stuff, but just never summon the effort needed. Hmm...maybe if my 4th day of running is Sat. morning it will gear me up for the rest of the day.