Everyone I have spoke with thus far in Psych who has been practicing more than 15 years cites the fact that they really enjoyed it, even as a 3rd year. They further state that the ones who get burnt out do it for the "lifestyle" while simultaneously entertaining the "idea of" Psych. Ie, they talk themselves into it.
I'm half way through my third year right now, and I can pretty much predict I'll be going into Psych. My other major interest is Path, but the job market/location freedom isn't as wide open in Path right now (I do it in March- so ultimately you never know). Also, I just find Psych both inherently "more interesting" to discuss all day long than blood sugar, HYT, colonscopies. Further, as someone on this board alread pointed out, it "comes easily" to me, which is important for a couple of reasons: #1- the patients welfare, and #2 my ability to take care to the next level while maintaining time for myself.
What could you see yourself doing all day for 10-30 years? That's the big question, IMHO.