What do I do if I have to stop dog walking for a client because she lives too far? [closed]

I had a meet and greet with the owner at her house and at the time of day the travel time didn't seem too bad, but at the time of day I would normally go, it takes me over an hour to get back to my house because I use public transportation. I do not want to tell her I can't walk her dog for her anymore since I just started, but then I am leaving pets alone too long in my home and it is affecting pick up/drop off times for boarding/sitting services I offer. I feel so terrible and I don't know what to do? She has another walker, but she has a different schedule every week, so she only needs me the days her other walker is unavailable, meaning I never know what or how many days I will be walking her dog. It wouldn't be so bad if she lived closer to me. I just need advice as to what anyone else would do in my situation. Please!! The last thing I want to do is waste a clients time or come off as an awful person. It's just not worth the time or money ( I only charge 12$ for a 30 min walk). And yes I know I should have known better, but she was the first person that has come to me for dog walking needs so I had no idea how this would fit into/affect my schedule. Help a sitter out yo! The last thing I want is to have a bad relationship with any clients!