I've been trying new core exercises recently. One of them is working with an exercise ball. This helps build abdominal and back control around/ below the injury site, but it also has a good effect on leg muscles. Exciting to me that there are more leg muscles responding!
Core exercises focus on the area around your spinal column. They are actually recommended for just about everyone. These exercise suggestions can fit into many workout routines, but are geared toward people who are in rehabilitation from back injuries.
Developing an exercise regimen can be difficult for anyone. After a spinal cord injury, there are many extra factors to consider. Mobility limitations, poor bone density, and improper temperature regulation are a few examples. But beyond that, how can you build on what you have? Flexing counts as an exercise. Staring at a toe and willing it to twitch counts as an exercise. What big or small abilities will help you reconnect neural pathways? Do you have equipment at home? Be creative but cautious (this is not an endorsement, but one of my earliest exercises was standing at the kitchen sink with my knees blocked: see my earlier post entitled "The Benefits of Standing," dated January 26, 2017).
If you are coming back from a spinal cord injury and need more specific ideas, this link leads to a resource on getting back to exercising after a spinal cord injury.