I say - be your own person. If your friends do not understand that tennis is your passion then ... ... well are they really your friends? My daughter is 12 and has a love for basketball that is un matched. She practices / plays some sort of basketball 6 days a week. This is not counting early morning training runs, work out sessions, and practice shots. As a result she does not have that many close friends but she is her own person and doing what she loves.