I remember a set of intervals that SD and I did in Italy when E was 6 months old - we set off on 5x4 minutes 1 minute apart and going out for 1 minute then reverse direction for 2 and turn back for final 1, so he had someone passing every minute. His little head turned from left to right and right to left tracking whoever was running towards and then away from him. He looked very puzzled :-)
Will have to do that one with Paul when Ted is a little older. For this one he slept oblivious in the corner of the golf course while I checked on him every 30s or so - the golfers looked very puzzled!
Oh actually not for this session - for the Thursday one
I remember the ones we did taking it in turns to push the buggy up a monster hill in Italy. Think he slept through that sesh!