Desperate to exercise but have a bad back

[Bellini12]

So I was all geared up to start exercising in January then... I slipped a disc in my back. Have seen physio and am on the right track. My back isn't painful, just stiff now, no siatica. She said I was ready to start Pilates but lay off jogging etc for a while. I find if I sit down for too long (driving) it stiffens up. Bending is still a bit tricky.

But my whole body is wobbly and I NEED to do something. Walking is good but I find it boring on my own - fine walking to the shops etc but it's not long enough. Does it actually help you tone up anyway? I'm not a swimmer either.

Can anybody suggest anything else?

Walking is good if you make yourself out of breath. When running, I use music/ podcasts/ zombies app to pass the time. Swimming is usually good for a low impact exercise, as is aqua aerobics.
Yoga and Pilates are good- check that the instructor knows how to adapt around your problem zones.