I feel shadow boxing is one of the best warm ups, cool downs and contact free conditioning training methods you can do.
When you are Shadow Boxing you are working far more than just your technical skill. Shadow Boxing done right utilizes a ton of visualization. You are bringing in offense, defense and counter attacking, along with footwork and a lot of movement. Ultimately, you should move as if you are fighting someone.
You can Shadow Box slowly, 50%, 75% or full speed. Every aspect of fight can be brought into your shadow boxing. Have fun and move with purpose.