Exercise & Calories Burned Question

I am very sorry if this has been covered already, but I couldn't find it...

I am wondering what everyone does for tracking exercise and calories burned. For example, I had to shovel snow this morning and I am told that it is around 500 calories burned but I certainly didn't feel that I had to work very hard... Does everyone just take the amounts given as fact or are there other ways to calculate calories burned?

I don't know why, but I feel like I am cheating myself with some of the amounts I am finding...