I love swimming.  It's great exercise.
I do too!  Do you often swim for exercise?
Not as often as I would like.  I should because swimming s low impact compared to land activities.
I've heard that a lot myself as I've had lower back injury.
Sorry about the injury.  Swimming would be perfect for you since the human body is slightly less dense than water and the water supports the body while swimming.
thank you.  I agree.  I've heard walking is really good for it also.
That's what I do the most for exercise, but it has been so hot lately...I worry about heat stroke.
no kidding.  I feel like we are baking in an oven...and a few months ago I was complaining about the snow!  
No snow down here, but honestly, I was at the beach last week and started getting a headache and dizzy-I had to get inside quickly.