Hospital kidnap ! by Veronica don't betray me!

Just a little fun riddle
I am something people love or hate. I change peoples appearances and thoughts. If a person takes care of them self I will go up even higher. To some people I will fool them. To others I am a mystery. Some people might want to try and hide me but I will show. No matter how hard people try I will Never go down. What am I?

Legacy Player: The "Play online" link above uses the new Quest Viva WebPlayer, which is currently in Beta. In case of issues, you can try the old WebPlayer.