Simply replace the unfilled areas such as "[]" and "[date]" with your information.
Dear [name],
It takes confidence and intelligence to embrace constructive criticism as a beneficial recommendation rather than a personal attack. When we fail to meet company expectations, recommendations help us change our behavior and get back on the road to success. Having the finest team members is important to [company name].
Each day should be marked with another advancement toward our personal and professional pinnacles of success. I am happy to be a mentor to people who have the ability to accomplish great things.
As your mentor, I must tell you candidly that the probability of success is not very high for you right now. Your performance is being restricted by the following: [describe areas requiring improvement].
I believe that your attention and commitment to changing the above inadequacies will bring about an immediate improvement. We will monitor your progress over the next [time your company policy allots for improvement plans] to determine whether any further action is necessary. Please do not disappoint us. The way you respond will have a lasting effect on your career.
Sincerely,