Anyone else?

Hello momma's so i have a 3 month old son and luckily he sleeps through the whole night, but when it comes to napping he can't do it on his own anymore. I would lay him down in his crib or he would just fall asleep on his own in his swing but now i have to hold and rock hin in order for him to nap. How can i get him to be able to nap on his own again?