Tummy time for my son???

My son is about to be 3 months old, and still hates tummy time... I have tried using a boppy pillow, I have tried using his favorite mirror to look at, I have tried laying down next to him and talking to him, I have tried putting him in his bouncer backwards and everything else you can imagine, and he sill freaks out, and then wont stop crying for at least 20 minutes... Does anyone have any suggestions?