Since I have received some personal abuse based on the post below, might I make the following points clear (I shouldn't have to, I know, but evidently people can't be bothered to read the post properly, or at all):
1: The title is a (crap, admittedly) play on the title of Milan Kundera's novel The Unbearable Lightness of Being.
And therefore,
2: It is not claiming that academic historians 'have a hard life'; it is about, well, what it talks about - the difficulty of living up to the ethical standards you (implicitly) set yourself by being an historian.
Thank you for your attention, but - really - if you can't grasp that from the post below then there are plenty of blogs about bringing up kittens, or liking looking at trees, or the joys of wearing a hat, or - oh, I don't know - living in fucking Kentucky and being addicted to cheese: basically any number of things that might be further up your street.