One of my (just recently turned) 4 year old son's faveorite catchphrase has got to be "I'm tired". And I'm afraid to say, sometimes, it just does my head in.
Every day on the way back from nursery, he expects me to carry him home (it's a 5 min walk), if I refuse he just refuses to walk, I normally negotiate carrying him half the way. He did use to go in the pram a lot, which I still used up until a few months ago because I don't have a car. I decided to get rid of it because he was always wanting to sit in it! And now, anytime we go anywhere, (usually he'll insist on taking his bike), literally 2 mins up the road (when the house is still in view) he'll start whinging "I'm tired."
I think nursery tires him out, plus he's getting used to being without the pram. But I let him watch a film everyday and read to him for a half hour so he gets plenty of chilling time. He is in bed by 7.30pm (sometimes he falls asleep straight away, sometimes it takes him half hour).
And every day it's the same. "I'm tired. Carry me. I'm so tired." Honestly, it's like being with an old man sometimes!