We see plenty of people walk from Cabana Bay, you can do it easily.
But as mac said consider the bus, everyone raves about the bus service from CBay and the other hotels that are slighty further out like Dockside/Surfside.
I love walking so I tend to do so however my travel buddy notes he gets enough walking in the parks to make doing so burdensome. It's also worth noting you can take the boat from Sapphire Falls which is just across the street though the walking path makes that a decent hike. I generally just cross the street at the light if that's my preference at the time though they seem to try to discourage that.