One way to combat lethargy when working long hours is to spend time on your purpose BEFORE going to work. You have to get up earlier, of course, but it would be a small sacrifice compared to the desire for which you work. But at the same time I understand that there are people who do not have this purpose in mind and routine can hold them up until they reach retirement without having built something to fill them up.

Of course, money without purpose is useless, it will not make you happy at all.