Seems pretty clear to me. You have to hit a total of 1,154 exercise minutes (an average of just over 37 minutes/day).
Mine's the same type of challenge but I have to hit 1,228; it's claiming I've earned 120 so far but as far as I can see the current total should only be 82. Either me or my phone is a bit rubbish at adding up and (in this case, at least) I don't think it's me!