"What I witnessed her do, the power I saw her summon from within her to bring this boy into the world was utterly astonishing," Osher wrote.
"Audrey was able to harness it, guide it, and use it to transcend the extraordinary pain she was feeling and channel it all towards an energy that brought this boy alive and well into the world," he wrote.
"That I've known Audrey for over five years, and yet had no idea that within her this whole time was an almighty divine force capable of bringing life into the world like this blows my mind and was astonishing to witness."
"For me - any marathon or endurance event I've ever raced is essentially a wander to the kitchen compared to what I saw Audrey do on Friday," he wrote.
Funnily enough, Osher confessed his new son came into the world with the sounds of Kendrick Lamar, Beyonce and Khalid playing in the background!
The new dad ended his incredible post: "Less than an hour after he was born, Wolfie met G for real - and she's the best big sister he could have ever hoped for.
"We are in love and drowning in gratitude, oxytocin and new baby smell."