A pep talk - When you give someone an encouragement via a speech, a letter or anything as such, in order for the completion or the success of a work or a project the thing which you say becomes a pep talk.
1. I had given him enough pep talks but he does not seem to be interested at all.
2. We should have a pep talk with our contestants so that they try harder.
3. The principal gave a pep talk to the students to work hard for the examinations.