Spreadsheet
I have a spreadsheet that record all my flights, hotel stays, car rentals. I also track and record my every drives/flights/rides/etc with some apps (World Uncovered, Fog of World) and google location reporting. I've been doing this for 4 years and total distance tracked so far is somewhere around 2 million km. My goal is hitting 40 million km but I'm not sure I can do within my lifetime.