I am a road runner (by foot) myself, and I like numbers and math as well (as an Engineering student). The idea of tracking/marking my running path for post-analysis has always fascinated me, but I always face a problem acquiring GPS-enable wrist watches: they are very very expensive, ranging from $150 up to $1,500 and so on.
That's a prohibitive price point for a hobbyist like me, so I decided to make my own GPS-enable tracker/logger for my road races. The idea was to unite my two passions (electronics and running) in a single solution to make my life easier and more fun.
This data logger works as follow:
1) Once you power the system up:
2) The GPS module searchs for satellites on the sky
3) The Arduino Pro Mini will manage to read data from the GPS module and write it to a micro SD card
4) this reading GPS and writing to SD card will repeat every 2 seconds.
5) step 4 until power down or end of battery juice
Here is a schematic diagram for the solution I implemented: