I recently took care of my friend’s dog and two cats for five days while she was out of town. I volunteered to do this for free, because she’s an awesome person and she has done so much for me. However, when she came back, she insisted on paying me. Because she knew exactly how much work this entailed. And while I would gladly do it again for her, and do it for free, she is the only person I would ever do it for free for. Because it is a pain in the ass.