Sometimes, even when you are a minor piece ahead in the ending, you are uncertain about how to use or convert this advantage into a win. In the position on the right, if white, for the sake of the argument, wins a pawn, this position could very well end up in a draw. On the other hand, if the moment arises, black can sacrifice his bishop for two pawns, and end up with an easier king and pawn ending to convert into a win.
With black to move, I played 42... Bf5 just to take the e3 square away from the white king. Then, 43. Kf3, h5 so white can't have the g4 square for his g pawn. It becomes even more apparent that white has to give up more ground, and black will naturally move into the territory. Play continued 44. Ke3, Bg4, taking away the f3 square... 45. Kf2, Ke4 46. f5, f6 black declines the free pawn to lock up the pawns. White is left with only king moves... 47. Kg2, Ke3 and the black king will soon mop up the white pawns.