For me, awareness that something is an impulsive behavior and willingness to change it is usually enough.
Practice identifying the impulses (bonus points for identifying their triggers, which often will seem unrelated).
Once you identify it, don't give in. Instead, indulge a good habit, no matter how simple it is (go get a glass of water, stand up and stretch, etc) and then get back to what you're supposed to be doing.
Initiating barriers is a great tactic, but one that I usually don't use. Barriers are effective not because they prevent you from doing something, but because they help you identify the behavior (you run into the barrier when you try it).