That's how it started for me. I played piano first, then added guitar because I wanted an instrument that is portable and fits in with the Celtic style of music that I really liked at the time. 
But after a few years playing my full sized Taylor it felt so heavy, especially when standing up on stage. I also felt it detracted from my stage presence it was so large and resting on my mid section. 
So when I picked up the dulcimer it felt so right instantly! Much smaller and the light tone mixed perfectly with my voice and playing it was so much easier on my hands and joints than playing the guitar.
I find that other people are starting to notice the dulcimer too, so now is a great time to re purpose your existing guitar skills and get into some dulcimer playing.

The question I get asked the most is 'how do I translate a song from guitar to dulcimer'. I guess there are two answers to that question. First:  You need a dulimer chord sheet. You can find some to get you started here .

Second, Is the guitar song in a key that dulcimer can handle? With dulcimer we can play (more or less) in the key of D, G, A, major, Bm, Em and F# minor and tuned down in the key of C, F and G, or Am, Dm and Em. The key of E major isn't so easy, or the key of C#, for example.   Sometimes, we need to transpose the song a little up, or down until we find a chord match for the dulcimer.

This is because the dulcimer isn't chromatic like the guitar. The guitar has ALL the notes on it. But the dulcimer does not. 
If you are curious to learn more, why not check out my free resource dulcimer players toolkit, I also have a course moving from guitar to dulcimer that tells you everything you need to know. to play your favourite songs on the mountain dulcimer.