Doing the math

I wonder how much walking it will take to lose this extra 5 pounds. If I do the math, it's rather daunting. 3500 calories for 1 pound. 17,500 calories for 5 pounds. 100 calories per 1 mile walk, give or take, depending on intensity. (how intense is a walk on the beach?) Looks like 175 miles? I'll make the math easy. Let's say I have 20 days. Not quite 10 miles a day? Not very realistic. 5 miles a day I can do. I guess I should have started earlier... and I have, sort of. Well, 2 miles in today already, some more to go.