We use reflexive pronouns in 3 cases:

1: When the subject and object is the same.

  • He talks to himself a lot.
  • You’ll hurt yourself.
  • I can’t make myself believe it.

2: When we want to emphasise that the subject was the only actor.

  • If you want a job doing properly, do it yourself.
  • He washed the car himself.
  • I had to pay for everything myself.

3: After ‘by’ to mean ‘alone’

  • I saw a little boy playing by himself.
  • She lives by herself
  • I don’t want to be all by myself anymore!