Leave the room
This is one step in the sleep
technique developed by dr. Ferber. You can train your baby to "self-soothe" by leaving and and progressively waiting longer between comforting your baby at bedtime.
You can start with 3 minutes and progress to 5, 7 and so on until your baby falls asleep. When returning, don't pick up your baby, just console him/her. It seems hard and even cruel, but it works.