It is important for any dog to be able to use each of their legs to stand, walk, and jump. This is a foundational set of exercises that is important for core strength, symmetry and balance.
See this article for the description of these exercises with videos.
Start with your 15 min walking warmup and then do these on a daily basis for your best results!
If your dog is unable to do these - please don't - see your rehab vet for help!!