Plenty of exercise without thinking about it

I went to a two day outdoor concert over the weekend. It was packed and I am truly exhausted. However I got plenty of exercise in, I'd be willing to bet a good chunk of money I walked at least 10 miles or more between the two days. Yesterday it was about a mile to the car and we walked that twice. 
Point being, I feel pretty good my legs are a little sore, and my arms hurt from lifting so many people up for two days but all and all I feel pretty good. 
 
Hoping to get back into the exercising a little more, I plan on going to another outdoor concert in July and I'd like to lose at least 15 pounds before I go. It will be hot and the less I weigh obviously the cooler I will be. I feel strongly that I can do it.