Watch the Different Instruments online guitar lesson by Vicki Genfan from Acoustic Rhythm Survival Guide
Try this with the same chord forms on any 6-string instrument that's tune-able like the guitar. So, that could be a 12 string guitar, 6 string banjo, electric guitar (with bizarre and cool effects of course), or???
Maybe you're a UKE player... well see if you can find the chords and play that. The sky is the limit. You could find these 3 simple chords on anything really – violin, harmonica, xylophone, keyboard... you get the picture, right?
I started playing piano at age 3 and guitar at 5. I used to play more piano, but got totally taken w/ acoustic guitar, but it always brings a slew of new ideas when I move to the piano to write. If you play multiple instruments, use this as a technique and see where it can take you.