Wow - I'm suprised that you haven't gotten more replies to this question. Sounds like your friend is getting you to do hr zone training. My first question would be have you done a max hr test? If you are using someone elses hr zones you may not be getting the workout that they are suggesting.
Doing zone 2 base training is a good idea and it will feel very slow and easy, but your zone 2 may be quite different from somone else's.