Favors

Why is it that when a friend asks you to do a favor, you do it without question, but then when you ask them to do something their answer is a flat-out "NO"? Is it just me that has inconsiderate friends, or does everyone have those? I willingly give, but when I ask a favor that isn't even going to hurt them in the least, they don't even stop to consider it. Not all friends are like this, some are just give give give all the time. I love those kinds of people. Anyway, I just needed to vent. I do that a lot, but it's been kind of a rough week.