Adding to Kayla's answer, it also depends on surface area of the object. You may have no problem carrying 5-10lb. books in school because it's small, yet holding a baby that is 1-2 feet in height may pose a challenge because it seems bigger than some books.
For instance, in the gym, I have no problem Deadlifting (lifting a bar from the ground) 290-315lb., but when it comes to helping lift a refrigerator that only weighs 185lb. it was a challenge that almost made me drop it on my foot. The item was much lighter, but the fridge covers a greater surface area so it's much harder to grab around it.
Weigh less than what? You? That's just because it's something heavy to you, personally. Some of the bigger babies aren't heavy to others when they're heavy to some people, it all depends on what weight someone can manage to hold.
lool i guess i am weak then cuz i was carrying my cousins baby and she is quite chubby and i had trouble
Because they are babies and fat babies are heavy for a baby.
thanks for help :)