Major distractions usually work well. Rasberries on the belly during diaper changes, unusual toys, a piece of sticky tape, a flashlight, singing. Switch it around a lot to keep dc distracted and try to be fast (for this reason, I did most of the diaper changes, esp messy ones - dh was just too slow and methodical). Nails I could only trim when ds fell asleep while nursing. When he was older, I could sometimes do them while he watched a video.