It doesn't feel as much like exercise; it makes it more fun to do. I hope you will find it that way too. One day a week is a good way to start to get used to it and give yourself some recovery time in between sessions. If the class uses weights and you have not exercised in awhile, you may just want to use the motions without the weights and work into using them after a bit until you get used to it. Ask about using the weights/not, but as Mazing mentions, you will already be using muscles you didn't realize you have and is a workout in and of itself. If you do use the weights, go for less resistance with lighter ones in the beginning to be safe to not over do it.

Have fun with with it and best wishes with your goals!!!!