How old is to old to start this?

I have always been a fan of fighting whether it be UFC, boxing whatever I have always liked it. I love to wrestle around and beat up whoever I am wrestling. I am wanting to finally start kickboxing sense my parents thought that me being in sports was more important than me having some self defense. I am not in the best shape of my life, but do like to work out (at tan and tone america lol) I know this will be so much harder training and I think that is what I am in need of. Am I to old to start kickboxing cles? i am not wanting to make this my career or even care about becoming a champion (it would be nice haha) i really just want to be able to fulfill something. by the way I am 20 - 21 in October.