I have relatively the same back issues.
I'm 33 soon to be 34 on January 6th and I feel like I'm 50. My everything aches. But mostly that stems from the years of back breaking work as a roofer, farmer, horse taming and care, concrete worker, construction etc. I've done almost all of it. Now looking for an escape to retire and focus more on my health or what's left of it.
As for my lower back i don't think we differentiate much here, but as far as exercises goes, sit-ups, planks, those are for abdominal muscles and if your having lower back issues then those exercises will cause you more damage.
Lay on your back with your knees bent to the ceiling, as if your about to do a sit-up. Instead of doing a sit-up, with no weights other than your own body, reach towards the ceiling and lift slightly the top half, I've your head, shoulders and neck toward the ceiling NOT TOWARDS YOUR KNEES. do this until you collapse.
Another is to get into the doggy style position, receiving. Yup all fours. Knees on the floor and all. What your going to do is alternate position and hold a position. Keeping your posture straight, raise your right or left arm and raising your alternative side the leg in a straight position outstretched.
And switch back and forth holding for 10 seconds or 30 seconds if you can each side.
Hamstring stretches, squat stretching is essential too.
Get to it. Don't be pansie. No pain no gain.
Yeah I feel ya... that being said, there's no reason anyone can't go back. Look at Mike Tyson at 58. Mental.
That latter doggy one I did see and give a brief try to see how it works. I didn't get much out of it tbh, seems too low-level, no strain involved? But, since you doubled the suggestion maybe I will give it another go.
It's especially important pre-ski, too, so I got a month to improve!
That's the whole curse, eh? Work just saps away the years and you realise you've ground down 20% of your bone mass or whatever, and it's too late! I'm taking on a bit more of a preventative mindset now rather than reactive...