How can i workout without parents knowing or get them to sign me up in a gym?

Not sure: If youre 36 im not sure why you don't want your parents to know youre working out? Obviously you can do certain exercise programs on your own or from dvds the gym is helpful but you have to get there many gyms collect monthly fees from clients who never go

Are your: parents not in favor of an exercise program? There are many types of exercises you can do at home without equipment: calisthenics, isometrics, resistance exercises using your own body weight e.g. push ups. Try discussing it with your parents, maybe they will surprise you.