I once babysat a friend's little brother when I was a lot younger.
Why did you babysit a friend's sibling?
Because the mother was too busy. She needed some help.
It's nice to babysit for others if you have the capacity. You should only commit to it if you know you're able to help. That way the child's mom won't be in a good position.
I was young, I had nothing else to do
Well you gave the mother a nice break and let her do things she couldn't have done without the baby.