Doing laundry: Always squat or kneel to get clothes in and out of the dryer. Avoid twisting back and forth from machine to laundry basket. When folding clothes, sit with clothes in front of you, or have them on a surface that allows you to stand up straight.
The guidelines may seem like commonsense, but when you're busy (or just not thinking about it) it's easy to make mistakes here and there. Just because your back doesn't hurt now doesn't mean that you aren't causing some damage. So don't let your back cause you any more grief. Protect it now so you can enjoy all the experiences that life has to offer.