Please check for comma errors. If I need to add any commas or take some out please show me where. Thank you!!

You seem to be progressing nicely after your back surgery; however, I do want to remind you of the importance of the instructions that was give to you prior to your discharge from the hospital.
If you follow my instructions exactly, you may anticipate the future with optimism. If you do not follow my instructions exactly, you will jeopardize your recovery; furthermore, you may do irreparable damage to your back.
I have prescribed some medication to alleviate the pain. After spending ten days in the hospital, you will be quite weak. Plan to spend your time in quite rest. Do not lift anything heavier than a glass of water. Do not try to drive or ride in a car until after I have a chance to appraise your progress during your next visit.
You will not notice any appreciable change in the pain level for about a week. However, you should be able to anticipate some relief during the second week that you were home. The pain will diminish slowly during that time forward. The more you try to do; however, the longer the pan will linger.
Your surgery was a complete success; however, be cognizant of the fact that recovery from back surgery is a slow process. If you over due your physical activities you may jeopardize that success. Your recovery is now in your hands.

"The more you try to do; however, . . ."

Comma, not a semicolon, after do.

" If you over due your physical activities you . . ."

Comma after activities.

The rest looks good.

Thanks

Here is the revised version with the suggested commas added and other minor changes for clarity:

You seem to be progressing nicely after your back surgery; however, I do want to remind you of the importance of the instructions that were given to you prior to your discharge from the hospital.

If you follow my instructions exactly, you may anticipate the future with optimism. If you do not follow my instructions exactly, you will jeopardize your recovery; furthermore, you may do irreparable damage to your back.

I have prescribed some medication to alleviate the pain. After spending ten days in the hospital, you will be quite weak. Plan to spend your time in quiet rest. Do not lift anything heavier than a glass of water. Do not try to drive or ride in a car until after I have a chance to appraise your progress during your next visit.

You will not notice any appreciable change in the pain level for about a week. However, you should be able to anticipate some relief during the second week that you are home. The pain will diminish slowly during that time forward. The more you try to do, however, the longer the pain will linger.

Your surgery was a complete success; however, be cognizant of the fact that recovery from back surgery is a slow process. If you overdo your physical activities, you may jeopardize that success. Your recovery is now in your hands.