He prowls Patagonia's headquarters, in Ventura, California, checking in on new designs (he showed me a sturdy down jacket that felt about as heavy as a paperclip and then said he'd kill me before telling me how they make it) and tinkering with a lightweight camp stove of his own invention at his desk.
Checking my email on my phone I found two messages from Twitter - each telling me that my password had been reset "as a precautionary security measure".
The UCSF team "really keeps meon track, " he adds, and knowing they will be checking his progress helps give him the motivation to stick to his regimen.