How to get almost 3 year old to sleep on his own?

My almost 3 year old son won’t fall asleep unless someone is laying near him and even then it takes him like an hour and a half to get to sleep and I have to shush him and tell him to stop playing around. Pretty much since the day he was born he’s always had someone sleep next to him. I feel like if I didn’t lay next to him he would never go to sleep on his own. (I read him a story, he gets into his crib, then I lay in a bed next to him.) I’m not sure how to break the cycle and get him to sleep by himself.