My thoughts are that language learning is so demanding, that it's normal that most people can't hold long periods of it, except for those that language learning it's a daily/weekly routine.
I compare fore example with doing sport. Whey you never did sport before, even 5 minutes of running can get you so exhausted, but when you're a runner, you can stand 1 hour of running very well. I think that the brain it's not that diferent in that regard. Maybe language learning involves some areas that are not used on non language learning persons.
So, saying that language learning routine it's like going to mind's gym, it's not a metaphor, it's almost literal.
Work it's also demanding of course. But people work everyday, so comparing language learning (special scenario) with work (standard scenario of most people's life), I don't know if it's a fair comparison. It's fair compare plain walking (on supermarket etc) with any sport activities? humans are always training on walking, we walk everytime. But, go visit to a person hospitalized for months, or recovering from an injury and see if is able to, even when the injury is gone, the muscles need to get used to the new activity that is walking.
So the answer to this poll, maybe it's a trick question. Maybe for a person who is doing language learning for years, there is no difference with work. But maybe it's not the case of new students, even in their second year studing the language, maybe are not completely used to it.