Try it when: Your back feels mildly stiff.
How it works: “Activities like walking, biking, and water exercise improve almost all muscle-related problems in the body,” says Katz. Exercise also stimulates feel-good endorphins, which may help reduce pain.
Good to know: To stave off stiffness most effectively, commit to 30 minutes of low-impact activity three times a week. (When biking, adjust the seat to hip height for the most comfortable ride.) And consider strength training. One 2010 study showed that people who lifted weights four times a week experienced a 42 percent decrease in back pain.