These days I have the time and the need to be back on the mat and spend more than five minutes on it. Since I often have trouble sitting upright properly - I can do it, of course, but it seems easier to slump - I have been working on strengthening my back, choosing poses where I can feel the muscles in my back are being challenged.
I have been doing the Seated Forward Bend (or Paschimottanasana) a lot, and I can stretch further every day. It is one of those poses where I am aware of its benefit for the nervous system while I am doing it (another one is the Plough); it is so soothing.
Apart from yoga, I have been running a lot, doing push-ups, which are incredibly hard, crunches and burpees for general strength, and swimming, which is also great for the back, especially the backstroke.
After only a week or so of consciously focusing on it - although I had been exercising all along -, I notice a difference. I wouldn't say my back is my weak point, but working on the computer and drawing at my desk take their toll. And when my energy levels aren't great I certainly feel my back is weak, if not in pain. Now, when I walk, sit or run - at all times, really - I sense this previously unfamiliar strength in my spine. It makes it easier to move about. And it has an added bonus. I feel mentally and emotionally stronger, like things cannot crush me that easily - as though they will just bounce off my new armour!