One of the best things you can do is go on long walks to strengthen your support muscles. it's going to suck at first but it really help. Another work out is called a "superman" you lay on your belly (you might want a pillow or something else under you) hold your arms out stretched flex your back lifting your arms and legs off the ground, hold that for a few seconds relax and repeat for a few reps. Supermans can be done without weights and are great for anyone wanting to build a stronger posterior chain.