Rav Soloveitchik on Teshuva (4)

Rav Soloveitchik on Teshuva (4): Is Teshuva a Mitzva? Must I Repent? by Rav Dovid Gottlieb

Fourth in a series of mini-shiurim on R Soloveitchik's approach to Teshuva based on his famous and incredible sefer Al HaTeshuva. Part 1 of our discussion of the second essay in the sefer.
If a person sins MUST he / she do teshuva or is that something that can be done of one wants? In other words, if I sin and don't do teshuva, is that a 2nd sin (because I am obligated to do teshuva) or is it merely 1 sin with a missed opportunity to get forgiven for that sin??