The most common causes of back injuries that lead to requiring surgery are muscular imbalances often created over a long period of time. Whether it be from repetitive actions such as a manual labourer, to an office worker who is constantly seated in the same position for hours on end, the structures of the back are affected by the imbalances created.
It is really important to note that a successful back surgery is giving you a fresh start. It is addressing the damaged structures of the back which were generating constant pain. What the surgery is not addressing though, is the underlying cause of why the damage occurred in the first place - the muscular imbalances.
You need to take action and address the muscular imbalances to ensure your back and the muscles that support it remain strong and functional. For many who have undergone surgery for their lower back, they resign to the fact that they will never be able to do the things they did before they injured their back. If nothing is done to strengthen the body and address the imbalances, then they are correct in thinking this way. However for the people who do correct the imbalances, they end up feeling stronger and more confident in their body than they ever did before they hurt their back.
Now into the specifics of what movements and muscle groups you should address:
Gaining both strength and endurance in exercises that are moving your own body weight are by far the best method to restore and maintain confidence in your back and body. Combine body weighted exercises with squats and sumo deadlifts with the goal to be able to lift your own body weight and you have the perfect routine to ensure that your back will remain strong, healthy and supported.
For more information on functional movement patterns, please go to the following link for examples.