As it turned out, everything was fine! I felt a little like a beginner since half of the songs were new, but other than that I did great. My foot didn't hurt any more than it did before I had the surgery, and I figure by the time I've learned all the new choreography, I should be okay to ramp up the intensity.
Sometimes the most difficult thing about weight loss is just starting. Start eating better. Start working out. Start taking care of yourself. I've been especially reminded of this lately because of all the things I've had to re-start. There will be plenty of excuses, and believe me, I've thought of all of them. But when it comes down to it, you just have to get up and do it.