Running, hiking, rowing, cycling (/ by 3), swimming (x by 3), cardio workout classes (1hr = 10km), non-cardio (eg Pilates, 1hr = 5km).
Routine commuting prob against spirit of things, though if you change to cycling in occasionally that could count - as would cycling further than necessary.
One type of exercise can only contribute a max 400km to the total. Different classes count as different exercise.
Enter exercise as what it's worth, as running or swimming. Eg, enter a 45min cardio class as 7.5km run. A 2km swim = 6km swim. 7km row = 7km swim. Leave cycling as real life distance.