Don't. Stop. Pushing!
It's tempting to pump the breaks, but don't stop now! Great things are ahead, and you'll miss out on them if you give up now. Enjoy the journey! Look at the scenery around you, enjoy the breeze on your face, and listen to the sounds of birds and nature around you! All metaphorically speaking, of course.
The journey is what you make of it. You can focus on your legs throbbing, the sweat running down your face, and how many miles you have left to go. OR you can focus on all of those glorious things we mentioned above. Of course, we're speaking about riding a bike right now, but this translates to life, as well. There's beauty in every journey, even if it's hard to see sometimes.