If I get overwhelmed, I typically just do something mindless, like sewing 1.5" strips together to make a scrappy quilt. It is easy, no stress, and helps me feel like I'm using up something others would throw away!
And take a break--go outside, garden, etc. Also, making a list on paper (not just your mind) and then prioritize which ones you would really like to do and not just possibly do someday.