Something I tried was whenever walking, I'll throw a punch when I put one foot down, and then throw a punch with the other hand when I put the other foot down. Sometimes I'll throw a right punch when my right foot lands (or left punch when left foot lands). Then I'll switch to throwing a left punch when right foot lands and left punch when right foot lands.

While this probably won't help technique or anything like that, it'll probably boost speed and endurance and help develop the muscles. (It also makes a great warmup).

What do the rest of you on this site think?