I'm not done lengthening but some days are good and some days are bad. If you're unlucky, you might have an entire day where you're at 6/10 or 7/10 pain throughout. That's rough and takes a toll.
You get used to the pain to some extent, but a level of discomfort remains. I've rarely been at 0/10 pain since the surgery but I'm often at 1/10 or 2/10 in terms of background pain. I also have sharp pains from time to time, up to 8/10 or 9/10 but that'd be for less than a second, when doing a specific move or something. That acute pain doesn't have as big an impact on your quality of life as the "chronic" pain.
More than the pain level itself, you have to deal with different types of pain. Surgical pain, nerve pain, muscle pain. They're different and managed differently. What's unsettling at first is that there is a randomness to the pain. One day your left knee will hurt, the next day it'll be your right foot.
Pre-op preparation is key, not only because (I believe) being in good shape helps, but also because you need to be ready to survive as a disabled person day 1. There are many little things such as urinals or shower chairs that make your life easier. Because every little action or move you do takes 5 times the energy as it normally would, living efficiently reduces your overall suffering.