Following his brief encounter with Briar in her Ether Sea, Klaus spent the rest of his time in solitude, focusing on a rigorous series of physical exercises to build muscle and strengthen his body
Exercises, by nature, were meant to strengthen the body — but just because he was training didn't mean he'd grow stronger overnight. Unfortunately, that's not how it worked.
Progress in physical development was a slow, grueling process. It demanded consistency, not bursts of passion. Muscles didn't grow because he willed them to. They grew because he broke them down, over and over again, and gave them the fuel to rebuild stronger.
And even then, it wasn't guaranteed.
