Not sure you can, you might have to re-invent yourself, and I'd suggest: Rob_k* , Run Rob, Rob KM, Marathon Rob, Ultra Rob ( aim high!) because it won't be long before you do nail a HM, then a full one, then an ultra.... And a huge well done for nailing it on the nose.
And then you did run a marathon and very well too. It’s a shame you didn’t ever like running as you were actually very good at it. I hope one day you go back to it.
Coincidentally I've just discovered how to change your name so I had to come back and tell you - go to the drop down with your name at the top ( by the health unlocked logo). Click on "Account" and scroll to the bottom. You'll see a section where you can change your name - click on the "save changes" button to finish.
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