You have to find out what's right for you, so it's trial and error. You are going to be all right if you accept realistic goals for yourself.
“Action is the normal completion of the act of will which begins as prayer. That action is not always external, but it is always some kind of effective energy.”
“The safest and most suitable form of penance seems to be that which causes pain in the flesh but does not penetrate to the bones, that is, which causes suffering but not sickness.”