A workout that’s too intense can put you in an anaerobic state, which means you aren't getting enough oxygen into your system. That causes joint and tissue pain. How do you know if you’re getting the right combination of aerobic activity and oxygen? Find your target heart rate (subtract your age from 220), then shoot for 40 to 70 percent of that rate. Research has shown that you can improve pain levels and weight loss in an aerobic capacity anywhere after 40 percent.