Just an idea taken from the earlier post about voice apps, I don't use them but I might do if it were a comedian or someone other than Johnson or an athlete - it got me thinking who would I find an interesting voice for running app voice companion so far I thought of and read - the list could go on for ages?...
Mr T from the A Team
Morgan Freeman (shawshank for slow runs )
Jack Dee for even slower runs
Paul O Grady?