As beautifully explained here Strava has crushed it’s ties to Relive and it’s apparent from the comments, that Strava needs to sharpen up. As DCRainmaker points out it’s your activity data to do with what you want.
If (and that’s a big “if”) we can assume that your data isn’t created using the Strava app, but for instance with a Garmin device, then getting data to Relive, and everything else for that matter, is easy and is explained here.
As they explain on Relive.cc “Relive works with Runtastic, Endomondo, Garmin Connect, Suunto, Apple Health (Watch), MapMyRun, MapMyWalk, MapMyRide, MapMyHike and Polar Flow.”
If you do indeed use Strava to create your activity data, first consider not doing that. Second hand Garmin devices are inexpensive and cut you loose from Strava’s ties. Pick one with bluetooth sync to make your own life easier.
As you will see in this post your data is yours and there many roads you can make that data can travel to achieve what you’d like.
Happy syncing – and good training.