A journey remembered fondly can still have been uncomfortable while it happened.

Memory keeps the shape of an experience and discards most of the discomfort. The long wait, the cold, and the argument in the car all thin out, while the arrival and the strange details stay. That is not a fault in memory; it is what allows people to keep doing difficult things and to look back on them warmly.

If you are in the middle of something hard but worthwhile, it helps to know that this is how it will be stored. It is also worth being honest with anyone you recommend it to, since your fond version has already lost the parts they will actually have to get through.