That's an interesting translation of that verse 14. Is that the NLT?
The NIV, NAS, and KJV all use the word "narrow" instead of "difficult".
The original word in that verse is interesting. Here's the definition according to Studylight:
Thlibo:
- to press (as grapes), press hard upon
- a compressed way
- narrow straitened, contracted
- metaph. to trouble, afflict, distress
IMHO, 'narrow' is a better translation. That's because of the contrast Jesus employed.
13 "Enter through the narrow gate. For
wide is the gate and
broad is the road that leads to destruction, and many enter through it.
14 But
small is the gate and
narrow the road that leads to life, and only a few find it.
See, wide is contrasted with small and broad is contrasted with narrow.
So, IMO, "difficult" doesn't convey the correct meaning. Jesus wasn't saying that once we're on the road it will be up to us to stay on the road because it's difficult to stay on it. He was saying that the road is narrow, pressing - like going through a wine press.
I believe that once we find the road and enter through the small gate, the author and finisher of our faith will keep us on that road. We may stumble along the way, but He'll pick us up again and set us back on the path.
Jesus is the gate through which we enter. He said "I am the door; if anyone enters through Me, he will be saved, and will go in and out and find pasture." (John 10:9).
Unfortunately, many people will not find the door, or they will try to get in another way. But it will lead to their destruction.
I believe all Christians (those who are born-again) are on the 'straight and narrow', even if we mess up along the way.