Lift with your legs. When you pick up your baby, stand with your feet shoulder-width apart, squat slightly, and bend forward from the hips. Hold your baby as close to you as possible when putting her down in her crib, without rounding your back.
Lighten up. Weed out that backbreaking diaper bag. For long outings, try a backpack worn over both shoulders. You can also balance the weight of the bag across your body by wearing it messenger-bag style or switching sides often.
Get support. Your bra size may change after pregnancy, so get remeasured if your prebaby bras are uncomfortable.
Suck it up. During feedings, sit up straight and tuck a pillow between your back and the chair. Contract and release your stomach muscles while you sit to help support your back.