You can't hear it. You can't see it. You only know it after you get in your car or on your bike and find that the air in your tire(s) has been steadily escaping since God knows when. And now, you can't go anywhere. *gasp*
God does know. Rest assured, He tried to tell us. He probably used any combination of inklings from the Holy Spirit, friends/acquaintances/strangers, random coincidences that couldn't have been... Point is, God doesn't like to see us lose our enthusiasm or joy or drive. But let's face it, if we're living on planet earth as a carbon-based (physically, of course) life-form, we will end up dealing with the entropy of our enthusiasm in some way shape or form. It's the natural order of things but it's not the supernatural order of things—in my opinion.
In order to proceed, we must distinguish between a blow-out and a slow leak—to continue with the tire metaphor. A blow-out is akin to a crisis. You immediately begin dealing with it. Emotions are neither here nor there. Sure, it's inconvenient, if incapacitating. But it's well-defined and (hopefully) a solution's at hand. Call a tow-truck. Change it yourself. Whatever. Nevermind that you might have been headed somewhere you shouldn't have. There is that possibility, and I don't mean to confuse the issue because deep prayer is required for both a spiritual blow-out and a spiritual slow-leak. But we're talking about something that crept up on you that didn't turn out as bad but still needs the same remedy. Sad thing is, many Christians have no idea when or where or how they began that slow slide into ineffectiveness and humorless complacency. The parallel in our Christian life is we become, over time, walking, talking, joyless, and therefore powerless, specimens of what God can do for a person. We shuffle by like a zombie and those who have "a good eyesight for a flaw in a deed", to quote Robert Louis Stevenson, will see right through our veneer of spirituality and faux Christianity.
This is a multi-faceted issue, but the main thing I'm campaigning for here is some vestige, however small, of praise, or worship, or prayer, or thanksgiving—anything at all, done in love, that maintains a conscious connection between us and God. This is the most worthwhile endeavor of life. Many things in life are of supreme importance but they are all ancillary compared to this one.
One of the symbols of the Holy Spirit is wind, or air. Even more literal is the Greek word for "spirit" as in Holy Spirit, which is "pneuma". Literally meaning "air". Something that inflates and keeps afloat. The trick is, in becoming so sensitive to Him that we're able to detect when something happens, however small, that would divert and distract us from inward focus upon God. And that's when the leak starts.
Think about your best friend. Or your spouse. How well do you know them? How in tune are you to the slightest thing that could offend and then conflagrate into the silent treatment (if that's their personality type)? When we think of—and interact with—the Holy Spirit, we must understand that we are dealing with the most sensitive individual in existence. Granted, much of the time spent living our Christian life is done inside His presence and His auspices and we probably don't even consciously sense Him. Understand that love is the great equalizer and He doesn't suffer from same temperamentality as do we. But He can be "quench[ed]" (1 Thessalonians 5:19), and grieve[d]" (Ephesians 4:30) and gone. Or at least it feels like He is. Rest assured He's there, though. Say "Hi" if you feel so inclined, but this on-running attitude of marginalizing the Holy Spirit into relative obscurity is the first step that ends in flat tires and flat-out sessility. That's not good. We've got new paths to tread and places to be led. And we can't go if we have no drive.
Stand in front of a car, get tired. Stand behind a car, get exhausted. Bad joke, I know but it's true. Get in.
It takes time to reinflate a (bike) tire by hand. So too, does it take effort to win over the Holy Spirit back into our conscious Christian outlook. If apologies are in order, let fly. And spend time soaking in the reality of His comfort and presence and love. Make an effort to pay conscious attention to Him. He'll respond. And when the slightest breeze you feel, let it flow and continue with your response of attention and love, whatever you choose. You'll be on your way in no time.