My four-year-old grandson rode his bike, and I did my usual running/walking with 40 seconds each phase. We had one rule that he had to observe. As long as he could see me, he could go ahead of me. If, however, he lost sight of me due to a curve or a hill, he had to stop and wait for me, or turn around and come back to me. When ever he slowed a bit and I passed him, I would say, "Ha ha, I passed you", or something similar. With a burst of speed he would reply, "Not for long". We went a total of about 2.8 miles. In the meantime, my wife and our two-year-old grandson did about a mile, and then the grandson played in the playground at the East Pavilion until the other grandson and I returned.
It was a great day to be outside. Nice in the morning when we life home, but warmer in mid day.