Donald Trump's popularity as a candidate for president is partly driven by his courage to say what he believes without fear, back-pedaling, or apologies. A lot of us don't have that kind of courage.

The consequence of constantly holding back, of having to hide your true thoughts, is frustration and anger.

Rather than say what we mean, or express what we want, many of us hold back to avoid conflict. We want or believe something -- but we fear rejection or punishment if we say what's on our mind. We hint and beat around the bush, hoping others will listen, understand, and respond positively to our requests. But we can't have disagreements.

Others bite their tongues in the name of political correctness. They keep their true thoughts to themselves to avoid making others feel uncomfortable. We can't offend or hurt someone's feelings.

For some people this is natural. For others, it's learned.

My teenage son sometimes struggles with saying what's on his mind. He wants to avoid the disappointment of not getting what he wants. Instead of saying what's on his mind, my son will ask, "What are you doing, Dad?"

I know my son well enough to know that when he asks me what I'm doing, there's something he wants -- but he doesn't have the courage to ask. So I tell him what I'm doing, and he says, "Oh, OK." There's no follow-up, except that he'll ask me the same question a few minutes later.

When my son wants something, he's afraid to ask because it hurts him to hear me say no.

When I was a teen, I avoided asking girls out. It didn't make it any easier if I knew they liked me. I avoided asking because the hurt of hearing them say no was greater than the pain of being single.

Most people prefer to avoid pain. Some, like my son, are highly sensitive to the emotional pain that comes with disappointment, so they avoid asking for what they really want. Some have suffered from abuse and are conditioned to hide their true thoughts to protect themselves from more physical or emotional abuse. They stuff their feelings.

The consequence, however, of constantly holding back, of having to hide your true thoughts, is frustration and anger.

Children and adults who hold frustration and anger inside can become depressed. They can feel helpless. It can make them physically ill. They can even become suicidal.

Others will let out their frustration and anger in bouts of rage, grasping for power over their lives. They may express their rage in violent acts toward others. As we've seen in school and workplace shootings, some become suicidal and homicidal.

It's dangerous to hide the truth out of fear. The Bible teaches us to speak the truth in love (Ephesians 4:15).

Speaking the truth in love doesn't mean we should avoid saying things or asking for things if we fear it might offend someone, or if we're afraid they might say no. Perfect love casts out fear (1 John 4:18).

The Bible records Jesus speaking some very harsh truths to people. Some were so offended that they had Him killed. But the truth needed to be spoken. When Jesus spoke, He spoke in love. The words He spoke that offended His hearers were intended to save their lives.

I want my son to be able to speak what's on his mind without fear. When he can do this, he'll be able to get his needs met in a positive way, share his opinions, and perhaps save lives. The alternative is to risk having him feel powerless and fall into despair and overwhelming anger.

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While working to help my son learn to communicate his beliefs and desires effectively, I came across some helpful advice from Dr. William Backus. In his book, "Telling Each Other the Truth," Dr. Backus recommends learning 10 phrases that help us say what we want with boldness and respect. These powerful phrases are:

"I want."

"I don't want."

"I like."

"I don't like."

"I would like you to."

"I would not like you to."

"I would like."

"I would not like."

"Will you please?"

"Would you be willing to?"

The goal of learning these phrases is to use them make requests -- not get your way. People can say no. But with practice, adults and children can use these statements to express their desires without fear.

I've explained to my son that Donald Trump's claims are sometimes exaggerated to make a point or get people's attention. But in watching Mr. Trump's campaign, we're getting a lesson on the power of assertiveness. It's his fearlessness in speaking his mind that we're learning from. He does it with an admirable conviction. That's why I'm adding one more powerful phrase to the list that Dr. Backus created:

"I believe."

Jon Beaty, a life coach and father of two, lives near Portland, Oregon. He is the author of the book "If You're Not Growing, You're Dying: 7 Habits for Thriving in Your Faith, Relationships and Work."