I've always had a hard time with mailing things. If I have stamps or mailing supplies at my house or I'm good to go. However, if it's a present or a letter without a stamp or packaging, I can think of about 100 things I'd rather do than go to the post office. And I generally do them all first.
I especially have a hard time getting things in the mail that look so cute on my kitchen counter and make me feel productive. I think this little set of baby gifts sat on my counter for over a week before I mailed it to my dear friend and her beautiful baby girl.