I have often gone into a musical production thinking, "Oh, good! A nice easy program," and come out of it saying, "Wow! That was really challenging!" I can't think of a time when I expected a program to be difficult, and found that it wasn't. I have sometimes been worried at the start, to find that what seemed impossible was doable with the right amount of preparation, but I can't say that anything has turned out to be a piece of cake.
A good example is the two programs most recently in my repertoire--one, a showcase of virtuosic Spanish music that I gave in Montpelier; the other, a musical celebration of nature coming up in a few weeks. After sweating over the runs, arpeggios, double-stops, harmonics, left hand pizzicato, etc., in the first program, I was looking forward to the nice, comfortable, and satisfying music of Beethoven and Brahms. While "nice" and "satisfying" still apply (especially the "satisfying" part), I was dead wrong about "comfortable."
The Beethoven "Spring" Sonata (No. 5 in F major) doesn't contain any big fireworks, it is delicate and extremely exposed. And it needs to sound exuberant and joyful, not pedantic. The Brahms "Regenlied" Sonata (No. 1 in G major) is rich and expressive, yet so very tender. It requires every ounce of concentration and energy I have.
Even when I play in church, a venue where I have the kindest audience; or when I'm asked to perform the simplest music, I have yet to give a perfect performance. I suppose it is better to struggle than not to struggle. When the music becomes easy, then that is when boredom is likely to set in, for both me and especially the audience. But I still can't help but declare, "Music is hard!!!"