Im going to be biking round trip with no hills which i calculated being 12.78 miles from my apartment to the beach how many calories would i have burned not including the riding ill be doing on the beach? I need to burn at least 670 calories per week any other ideas? I also hike,swim and go to the gym i rest 2 days a week so i don't burnout, im also a vegetarian so i don't eat alot of junk food and meat, and i drink plenty of water....