spread oneself too thin

Fig. to do so many things at one time that you can do none of them well. It's a good idea to get involved in a lot of activities, but don't spread yourself too thin. I'm too busy these days. I'm afraid I've spread myself too thin.

Overextend oneself, undertake too many different enterprises. For example, Tom's exhausted; what with work, volunteer activities, and social life he's spread himself too thin . This expression alludes to smearing something (like butter on bread) in such a thin layer that it does not cover the surface. Jonathan Swift used spread thin in a positive sense, that is, something should occur less often ( Polite Conversation, 1731-1738): "They [polite speeches] ought to be husbanded better, and spread much thinner."