Here is what I did. I don't have a smart phone, but I do have an mp3 player. I found songs that were the correct length, and I switched from walking to running when the song changed. I used that for a while.
later I downloaded sound bites and inserted the sound "I'm so ready," when it was time to run, and the sound "you're almost there," when it was time to walk. It takes a while to set up, but it works.
You're never too old to do goofy stuff.
-Ward Cleaver ("Leave It to Beaver")
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