I need a friendly letter for a teacher i had in the past

Outside influences that affect self-esteem come from peers.

The way someone defines the type of person he will become and the way to feel about it is greatly influenced by peers in different ways. If the effects on self-esteem are negative, the origins may be found in the following:

Exclusion: It is demonstrated that when adolescents are victimized or bullied, they develop high levels of social anxiety. Peer-pressure: If surrounded by toxic friendships, it is highly probable that a person may be led to do things that are destructive or unhealthy.

By the other hand, having a good relationship with peers and meaningful friendships can help protect a person if their relations with parents are distant for example.