Trying to lose weight

I'm heavier now than I was at nine months with any of my babies. Fifty pounds heavier than I was in high school. I feel like a stuffed toad. If I could only put about six more inches in height I would be in great shape. I've been working out and have decided that my muscles are so out of shape that they do not even realize they exist. It's horrifying! Walk, run, ride bikes for 7 miles a day and not a twinge. Does this mean I'm not trying hard enough? The puddle of sweat that I create begs to differ.