You're lost in your head on Monday. A couple of big ideas are churning around in your brain, and rather than engage in idle chitchat you're most likely going to decide to turn a little inward and let yourself daydream through midweek. That's perfectly okay. Explain to others that it's not personal: You just have a couple things on your mind. It's a pretty sure bet some people are going to think you're being aloof nonetheless -- and you are, in a way -- but that's your prerogative. Later in the week and over the weekend, you'll feel more social again.