Funny you ask. I've been a runner before, and while it is typical to not be smiling while running, I always felt far better after the recovery from the run. Now that I am no longer a runner, you would see pain on my face if I was running.
Being in SoWal, I see many runners. Some glide through their run and others, ... well, some people just weren't designed to run. It's great that they are trying, but if it is that much of a struggle, there is something called "walking" which will do them very well.