Explain how, as a Christian, one's faith would affect the way a person interacts with people within their chosen profession (such as a mental health counselor).
Being a Christian, a follower of God, is not just a Sunday proposition, and the Bible is not just a Good Book. Believers in Christ (Christians) should always represent Him to the people around them, whether that is at work, in their neighborhoods, or at the grocery store. Sadly, that is much easier to say (or write) than to practice on a daily basis.
Every profession involves interacting with others, at least to some degree. That means that every interaction (conversation, meeting, discussion) a Christian has should reflect the teachings of Christ.
First, Christian professionals should always demonstrate love and respect for others. Romans was written to Christians about other Christians, but the principle is the same when praying for unbelievers: "Love one another warmly as Christians, and be eager to show respect for one another" (12:10). The reason this is so important, of course, is that if God loved us enough to send His Son as our sacrifice, we should demonstrate that same kind of love to others.
What that looks like in the professional world will be different based on the working environment. You mentioned the mental health field and I am in the field of education; for those kinds of professions, where there is much opportunity to interact, this mandate to love and respect is applicable to colleagues, clients, patients, and students. When these people express anger and frustration, we (Christians) are to listen with respect and then speak in respect and love.
That does not mean we cannot speak hard truths, things which are difficult to hear. True love and respect mean saying the difficult things without anger and without taking in joy in the other person's pain. Love and respect should help us empathize with other people in their troubles and rejoice with them in their joys and achievements. It should not be difficult for a Christian to give praise, but it should be quite difficult to belittle or berate someone, especially for something they already know is a weakness or problem.
Second, Christians are to pray for others, both believers and non-believers. One of my favorite verses is James 5:16 which reads, in part:
[T]he effectual fervent prayer of a righteous man availeth much.
Another translation says it this way: "Anyone who lives the way God wants can pray, and great things will happen."
Praying for others does not need to be a public display or great show; in fact, the Bible warns against those kinds of things (note the Pharisees). Instead, praying in the midst of difficult situations for healing, help, and hope for our patients, colleagues, and students is one of the greatest tools a Christian has to effect change. When we truly pray for others, we are forced to see them as God sees them; when we pray for ourselves to have wisdom, love, or help, we are admitting that we do not have all the answers and need guidance. Prayer is useful in calming a situation as well as in seeking God's wisdom for the difficult things.
In general, believers in Christ are supposed to be like Him. The Holy Spirit dwells within them, and they are to bear the fruit of their experiences and life in Him. Christians are to demonstrate the attributes found in Galatians 5:22-23:
...the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, meekness, temperance....
That is true in their homes, their schools, their jobs, their churches, and their relationships.