The best methods, time off smoking (for which there is NO substitute), and burning calories have been mentioned.

Another effective method is using the fact that we can also develop tolerances to the different deliveries of smoke. For instance, while bongs generally yield the highest volume hits, if you always smoke b's, and it's been a while since hitting a pipe or j, it can be surprisingly different.

I will usually withold one method from my rotation, then boom, pop it back in when it becomes too familiar.