I took this challenge myself in Febuary and although I am a giver by nature (husband says I give everything away) it did make a difference when I focused on it. So I think you should give it a try even if you think of yourself as a big giver. It don't have to be much, some days was a note card that I sent out to someone. The challenge even says that you can give a smile or kind words but I didn't feel that was challenge enough so I did try to give tangible items. And signing up at this site is not a requirement. I just used it as inspiration for myself. But check it out.
The 29 Day Giving Challenge