You could be tired or fatigued. You've been through a busy patch that has felt like running up a steep hill. Maybe you've been working too many long hours, running too fast for too long, and now have some 'adrenaline exhaustion'. You need some rest and a long drink. God understands this. That's why he created the Sabbath and integrated a rhythm of activity and rest into all of creation.
You could be slowing down because you are uncertain. Maybe you are moving through some new territory and into changed conditions. You could be coming up to an intersection or a crossroads. It's normal to slow down during these times. You need to look around. You can’t go too fast or you’ll miss things. Go ahead and slow down a little … just to get your bearings. It takes to time to adjust and re-orientate to a new situation where you are unfamiliar and a little uncomfortable. See also: Seasons.
You could be slowing down because you have lost your passion. You're just cuising or coasting. Your level of passion and excitement has diminished. You've lost some vision and purpose for some reason. Complacency, lethargy, indifference, apathy, or lukewarmness have settled in on you like a wet blanket. You've lost the fire of your first love. Thankfully, God is a fire-lighting God who can ignite fressh passion in us, if we ask. See also: A Personal Check Up.