I'm thinking about taking my greyhound for a 6 mile walk in the north york moors. We'll be going up and down hills but taking it steady. Do you think my little grey could cope? She's young and fit - but I'm worried about her collapsing/refusing to walk any further halfway through and being stuck in the middle of nowhere!! We normally do a 2 hour walk at the weekend but she only gets 2x20-30 mins every day during the week.