After a back injury some time ago I notice that I can do everything I once used to do, but I'm much slower at it. Do you think it really matters how fast I walk or move about?

This may depend on your overall health status and age. Slowing down is a natural part of the aging process, especially after an injury. But if at age 30 you're at a snail's pace or moving like a 65 year old, then you may start to experience physical deconditioning. Deconditioning can lead to disability.

Patients who fear pain or think it's going to hurt before it does, often start avoiding activities. Or they may perform tasks more slowly and less vigorously. If there's not permanent disability it may be best to get back to your former level of activity and function. Your future health may depend on it.