Do You Affect or Infect Others?

Words, words, words! In my opinion, when we talk about the connection between attitude and behavior, there are two words that come to mind, "affect" and "infect." My first reaction is to think of "affect" as a positive verb and "infect" as a negative verb, but I guess they can be both.

According to www.dictionary.com:

af•fect - verb (used with object) - 1. to act on; produce an effect or change in; 2. to impress the mind or move the feelings of; 3. (of pain, disease, etc.) to attack or lay hold of.

in•fect - verb (used with object) - 1. to affect or contaminate (a person, organ, wound, etc.) with disease-producing germs; 3. to taint or contaminate with something that affects quality, character, or condition unfavorably; 4. to corrupt or affect morally; 5. to imbue with some pernicious belief, opinion, etc.