How do I approach my husband to let me to get the mail which is on the other side of the busy road? He walks very slow.

We live in a rural community and for 19 years my husband has gone to the mail box to take mail and to get the mail everyday, he has always enjoyed this task. Our box is on the opposite side of our busy road. But now he walks very very slow and I have been told today that he has almost been hit. How do I approach him without taking this dignity from him and at the same time protect him. I am very new to this and he has in the last few months been less aware of what is happening. The days of the week, telephone numbers, names, less attentive of his apperance, constant complaining, always hurting and more things going on. He has not been officially diagionsed with Dementia but I see the signs as my mom had dementia. I know that he still has some normality about him so I feel as thou I am being mean but in the same breath, I want to keep him safe.