Stuck in a rut. Needing some advice...

My bf (27) and I (20) have been dating for 2 years now. We are finding ourselves stuck in the same place, basically on cruise control for the past year. We are too comfortable in this relationship. When we talked about how we can fix this or how we can climb out of this rut, we didnt really know where to start as far as ways to kickstart this thing again. Any advice is welcome. I don't want this to be the breaking point of the relationship, and I'm pretty sure he doesn't either.

TL;DR: bf and I are in a rut. We need advice on how to rejuvenate the relationship of two years.