I agree a long luxury holiday would make anyone happy.
I don't think Harry looks particularly miserable most of the time though. And I don't really agree with the idea that the Sussex's are lazy yes they are having an extended break but last year Harry did something like 20 less engagements than William and Meghan who had maternity leave did 40 less than Kate. They are working as hard as any of the royals. They are just doing it in a way that works for them I think.
I agree though I think a lot will depend on how they come back from this break and how they move forward next year.