What do you do if I can't keep my newborn up while breastfeeding?

I'm a first time mom and my son was just born he's 5 days old. When I was in the hospital I was told to breastfeed him every 2 or 3 hours for at least 30 mins. He would fall asleep long before that. It's been hard since I had a C-section. When he falls asleep I tried to wake him up by tickling his foot or underarm, wipe a cold cloth on his face, blow a little on his forehead. Non working and I worry I'm not feeding him enough