The squat and deadlift are great for the back, as long as you use proper technique. See Starting Strength by Rippetoe. You should be able to sit on any chair without back pain. An ergonomic chair is no answer --- it is a crutch that helps the problem grow.

Working out and weightlifting helps me too. You can't really lift in an olympic sense with bad mobility.

I try to do a combination of sitting and standing to keep my hips from getting too tight, which can end up creating an anterior pelvic tilt that will cause back pain. I'll do couch stretches[1] to open my hip flexors and banded pull-aparts[2] to alleviate some of the rounded shoulder issues that we all get from sitting and typing all day.

1. http://www.bodybuilding.com/images/2016/june/flex-those-flex...

2. http://www.bodybuilding.com/exercises/detail/view/name/band-...

I can vouch for this. Keeps the mind strong as well. Never have backpain and completely fixed my (mild) kyphosis.

Additionally:

* Try to keep about 20% tension in your abs/core all the time. Even when sitting. Punch your SO in the belly, that always works two ways!

* Don't sit all the time. Walk, stand, etc.

* Certain exercises and stretches can work wonders if you have a _good_ PT who can point out where the problem is.

I recommend that before going to the gym and picking up the heaviest thing you can lift - focus on your core for a good 3 months. Do crunches (properly) and plank every day. When your core is more stable, then do indeed go pick up some heavy stuff (with proper form and a spot of course!).

As long as what you life is not too heavy. Than it becomes very unhealthy.