re: mid 30s and tired / burned out...

I am in pretty much the same boat and I get in the same rut that you mention every couple of years...

trouble with me is, I typically take very little time off from work...same old grind all day every day for months on end...

what I typically do is to just loosen up and head up to the high mountains of colorado for some fly fishing...you can do it by yourself and it is perfectly enjoyable and relaxing...