I have found that my back pain is lessened the more walking I do. And by walking, I don't mean just mooching around the shopping mall or around town - I mean getting up into the hills and working up a sweat!
Hillwalking is amazingly popular in the UK - as is evidenced by the popularity of magazines such as Country Walking and Trail, and organisations such as the Ramblers. Hill-walking (or hiking) is practiced on many different levels - from gentle country strolls to extreme hikes in the Highlands of Scotland.
The UK is criss-crossed with thousands upon thousands of footpaths and bridleways - it's easy to get out and about, even if you're in the centre of a city. Walking gets you away from traffic and the hustle and bustle of modern life. It's great for lowering your stress levels - or at least, I find walking is a great way to de-stress and is the perfect antidote to sitting at a desk all week.
I'm lucky - we've got several footpaths along the river and through the fields near us, but even when I lived in the middle of Leeds there were footpaths not too far away. Back then I used to walk into the city centre on a Saturday morning - and most of my route was along the Leeds to Liverpool canal towpath and away from the traffic and noise.
But it doesn't matter what you do - when you're walking, you're exercising. And because the ground you're walking on is uneven (muddy trails, farm tracks, rocky hillsides) you are constantly using the muscles in your back to keep you upright. And I find that the more I use those muscles, the less pain I have.
(However, I have found that unless I do *a lot* of walking, walking isn't enough to get rid of my back pain completely - so it's part of my overall regime. The one time it did work is when I was on a walking holiday in the Faroe Isles - but we were walking every day up some serious hills, and on a day-to-day basis I just don't get to do that often enough...)
Unfortunately I don't find walking around town is quite so beneficial, but it's better than doing nothing.
So as often as I can, I get up into the hills - not only is the exercise good for my stress levels, it helps my lower back pain as well.
Get kitted out. You only really need two pieces of kit - a good pair of walking boots and a weatherproof coat.
Walk in company. Walking is safer in numbers - if you don't know anyone you can join The Ramblers.
Don't over do it. Don't try to do too much - I know this one from experience. Walking doesn't always feel like "real" exercise, but you can injure yourself and if you're not "hill fit" then you shouldn't be too ambitious.