Have not heard of Strong app before... will look into. I used to use $miles or Smiles but then they wanted my phone number to withdraw 1000 sats which took at least a few weeks... big bummer in that regard.
Someone actually posted their steps per day for the past week or so and their average and did an invoice cor that. Happily paid it :) Proof of Walk! Next up is Proof of Lift? :)
