That's a big assumption. Alyssa may very well not spend all her walking time writing code (setting aside the implication that writing code is not "enjoyable" for now).

Feynman was a very successful physicist. A nobel price medalist, among other things. He very famously was also someone who enjoyed a life outside of physics a great deal.

Paul Erdős, on the other hand, did at least outwardly seem to have spent most of his life focused on doing mathematics. And nobody can convince me that he did not enjoy his life as well...