I have never exclusively co-slept. I always started out my babies in their own bed and then we they woke in the night moved them to mine to feed them and sleep the rest of the night. But as with any type of weaning I would do it gradually. Does he nap alone? Start by making his room and bed an exciting place to be. Decorate in a way that would excite him, play up the 'big boy' aspect. When my babies were newborns they all slept in a swing or with me. Around 4 months old I started to train them to go to sleep on their own. I did it gradually, in baby steps. The same sort of thing would work here. Break it down into baby steps- start by breaking the holding/ lay facing him part, be near him, soothe him but don't give in. Then maybe move him to a mattress on the floor of your room. So he still feels safe with you, but not physically with you. Then go for his own room- stay with him in the room until he is asleep for a few nights then gradually leave and come back in 5 min, 10 min, etc. Eventually he will learn to fall asleep on his own. It will probably be hard, but you have to be consistent or he will learn that his crying will let him in your bed. Co-sleeping only works as long as everyone is happy, so if you aren't anymore then it is probably time to stop.