Job hunting sucks! It sucks a lot less when you have a job though.
But isn't that disloyal?
No, it's a way to keep pushing yourself and reaffirming your career decisions. Whether you love your job or you're looking for a way out, make sure your resume is up to date. Submit some applications to interesting jobs and take some interviews occasionally if you can. You're already employed, so no pressure. You'll have opportunities to test your knowledge, learn what gaps you'll need to bridge in your career growth, and improve your sense of self worth.
But what if I get an offer? I like my job and I can't imagine leaving.
That's great! Knowing there's an opportunity to leave for a competitive offer means you've got options, and you're not trapped. It means you're doing what you're doing because you want to, not because you have to. That's a powerful thing to have in the back of your mind on a bad day. Loyalty isn't refusing to consider your options, it's the confidence you gain by choosing.