Before I was married, my quest was finding my "soulmate" - that kept me occupied for about a decade...not that I didn't look for other things in the meantime - research (introverted thinking) is the INFJ's tertiary/hobby function. Once I met my husband, the new "thing" became finding ways to celebrate special occasions - anniversaries, birthdays, holidays, vacations - I'm sure that, combined with the spiritual aspect, is what drew me to all things liturgical. I love the concept of making something new out of the old and of building traditions that are rejuvenated by creative interpretations.
What's interesting is that the brainstorming, the planning, and the anticipation often turn out to be more fulfilling than the thing itself. In the case of something permanent - like marriage and motherhood - thankfully that hasn't been true (though I have a strange recurring dream that I'm turning 40 - which I am shortly - and I'm still single, but just when I'm on the verge of hopelessness, I remember eHarmony - this dream is *very* annoying). With short-term quests, though, I sometimes spend more hours researching (and building up expectations) than actually doing whatever it is. I've read that actually most people enjoy the anticipation of a trip more than the trip itself.
INFJs, with our dominant introverted intuition always idealizing, our extroverted feeling making us want to be emotionally fulfilled while pleasing others, our preference for judging that drives us to perfectionism, planning, and getting everything settled, our introverted thinking function that analyzes everything to death...when all that goes into something that will be realized (lived out) with our inferior function of extroverted sensing - it can be somewhat of a letdown. I'm drawn to camping because it taps into that part of me that's not as developed - the hands-on sensory world - and in the best way, by enjoying God's creation. Still, all of my vicarious virtual camping is not going to translate to the perfect family getaway. I will struggle with setting up tents, getting dirty, lacking creature comforts, hearing the kids whining, quarreling with my husband over the best way to roast marshmellows (just kidding), fighting off mosquitoes, hauling stuff around, etc. Most of all, when it's over, I will feel the urge to look for something new to do, but really I'll be seeking something to think about, dream about, look forward to...
If we find ourselves with a desire that nothing in this world can satisfy, the most probable explanation is that we were made for another world. ~C.S. Lewis