Okay, that title might be a little extreme, even though I know a lot of people would like me to destroy MY instruments, but there is a certain wisdom to be found in those words. In fact, it reminds me of some of the best songwriting advice I ever heard, which came from none other than Barry Gibb of The Bee Gees. (Not directly, mind you, it's not like Barry and I sit around shooting the sh*t about how to groom your chest hair, or anything.)
Now, I know some people might scoff at The Bee Gees for their disco tunes, but those people are sorely misguided because The Bee Gees are, in fact, extremely gifted songwriters who have written some of the most diverse, enduring and popular tunes of the last 40 plus years. Not only that, they can wear the sh*t out of white pants suits.
Anyway, what Barry said, and I agree with from personal experience, is that songwriters should, from time to time, write away from their instruments. What this means is it's a good idea to get away from your favorite composing tool and try to come up with melodies, rhythms, and harmonies in your head, if possible.
While this may sound difficult - especially if you're in the early stages of songwriting - it does help to free you up from learned or ingrained patterns of behavior and keeps you from falling into a rut. For example, if you write on the piano, you may find yourself always starting with an a minor chord and then going to a G magor chord immediately after. If you write in your head, you may surprise yourself and shift to a g minor chord or something equally adventurous. Or, you might do six bars of a melody before changing the harmony, instead of your usual four or two.
Similarly, you can try writing on a different instrument than you're accustomed, if you are able to do so. Hell, sometimes it's more exciting to write on another instrument that you DON'T know how to play because it ooften takes you places you would never go once you get a little theory in you.
So try stepping away from your instrument to write; don't let it be a songwriting crutch. Try writing in your head riding the bus to work one day or late at night lying in bed (quietly of coruse, so you don't disturb your significant other). You may actually surprise yourself and come up with something innovative that you really like. Plus, you can always go back to your instrument of choice and fill in the blanks if you get stuck. That is, unless you took the first line of this blog to heart and threw your guitar in the fireplace or something...