I had a patient, Len, who was in the office the other day and he showed me a nifty baseball hat that he used when doing gardening work outside. It had a modification in the top of the hat that included a protective cover, so that if he hit his head on a large branch, it would protect him from a head strike. I was impressed: it looked good, was comfortable, and clearly would protect his head in case of a moderately-hard injury.
As we age, being smart, thinking about the risks of an activity and planning accordingly are the ways to stay health and active, without setting limits more than is necessary. Take a look at the products from Northern Safety. I think you might find some useful items that will keep you healthy and active.