Often God assigns us to tasks we feel we cannot do. We object for this or that reason.
We are often right in our objection. Maybe God calls us to work ministering to youth and we feel we are not gifted at communication.
It may be true but we fail to see often what is needed. Communication is only one part of a great picture. Sincerity, love, patience, and many other traits are usable by God.
Often we simplify things into one criteria and feel we cannot do tasks because of that criteria, but often many traits lead to success.
God often calls people to tasks for various reasons. We may not feel qualified or may not be qualified, but he is the one who calls and ultimately he is the one who brings success.
Sometimes God calls people specifically not qualified to the task to show his power, because with God all things are possible. But often he calls qualified people who cannot see their qualifications.
We often do not see what strengths will be necessary to complete tasks. It is our limited perspective that blinds us at many times to what is possible.