Jan, if you're doing 4 or 5 wheelbarrows before you melt, you're doing great! You don't have to do it all at once.
I converted my yard from lawn to mulch and beds about one square yard at a time. Per week, in the summer. I'd strip the grass and weed it, digging up as much grass roots as possible. Amend with compost, plant, fertilize, mulch and adjust the sprinklers. Then go fall in the pool for an hour to cool down . . . float around in there until my head stops pounding. I still do my gardening in summer in 10 minute increments.
So, it's been a mass of jungly weeds in the summer, but I have found a fellow who will do hand weeding for me once a week, and we're getting it under control again. As the weather cools off, the plants slow down, and the gardeners speed up. Going forward, it's a game of clean-up in the fall, catch-up all winter, and a struggle to keep up all summer. Just be sure you're having fun in there somewhere!