I would focus on strengthening your body's natural defenses.
Take a high-quality multivitamin
supplement (I take both and they are made by Twinlab), drink plenty of water, and listen to relaxation music on a regular basis (below I included a link to a good CD plus links to Twinlab)
All of these steps will promote healing and feeling better. And definitely bring a bathrobe and slippers with you to the hospital. It will help you feel more comfortable when the doctor wants you out of bed walking around.
Don't be afraid of asking for pain meds after surgery. Pain can interfere with healing, so take your pain meds as needed!
One more thing- cut back on tabacco, alcohol, and sugar-rich foods (including soda) between now and surgery. This will also improve your recovery.