Think of it this way: If you're always in a passive job seeker mode, you're coming from a position of power. Look at baseball as an example. When a batter is immersed in a hitting streak, things come easy to them, they're relaxed, their swing is fluid, they're in the zone. They're confident and confidence begets more confidence.
The same thing happens when your confidence is at an all-time high at work. You're not in an anxiety-inducing "gotta get a new job tomorrow" frenetic mode, you're not ignoring red flags during job interviews because you're idolizing a future employer without fully evaluating them (remember, you should be interviewing them just as much as they're interviewing you).
Instead, by keeping your eyes open and updating your resume, accepting coffee meetings, applying to jobs "just for fun" (yes, for fun), connecting with employers and saying yes to interviews, it's light. It's in motion. And it's powerful!
When you interview under these circumstances, you're just casually seeing what's out there. You're checking out what you're worth and what your options are. And, because it's casual and on your terms, you're not second-guessing those answers to challenging interview questions – you believe in yourself! Prospective employers can sense this and it puts you in more demand (very similar to dating, but that's a whole other blog …).
Keep this in mind: As much as you enjoy your job now, you never know what tomorrow will bring. Unfortunately, the situation can very well be temporary and that's how you should view it. Life is unpredictable and that can include this fantastic situation. That awesome boss? They may get transferred, move, resign, you never know. Your department may merge with another one. Good times will not last forever, so by going on interviews and keeping your skills sharp, you'll have an active, robust network to tap into (and you might even find a role you like). What's the worst that can happen in all of this? You decline a job offer? Spend some time sporadically out of the office?