Here are the completed sentences using reflexive pronouns:
Lisa: I hurt myself while I was playing basketball.
Lisa: No. I took care of it myself. It's not serious.
Tom: That's good. I once fell and cut himself while riding my bike!
Tom: It was. But I cleaned the wound myself and everything was fine.
Lisa: You're brave! Yesterday, our dog opened the door by itself. Can you believe that?
Lisa: Yes, and my little brothers made lunch by themselves today. It was a mess, but they tried!
Tom: Sometimes it's fun to do things by ourselves. We all learn that way.