Disagreement is normal. Disagreement is healthy. I am 100 percent opposed to "yes-men"--weak-willed subordinates who agree with whomever happens to be in charge at the moment.

And yet. When it comes to startups, team unity is of the utmost importance. It's like the Woody Allen joke equating relationships with sharks--if they aren't moving forward, they're dead in the water.

Nothing kills progress like bickering and contention. Even small differences of opinion, if left to fester, can breed resentment, feuds and drama in the workplace.

Here are four ways to encourage and maintain productive harmony with your team:

1. Be smart and thorough when hiring.

It's amazingly difficult to build an awesome, healthy company culture where relationships thrive and folks look forward to their jobs. It's amazingly easy to screw it up by hiring a bad fit.

If your focus is to sustain the magic of a team, hiring itself should be a team effort. You may be a fine judge of talent, but talent all on its lonesome is never an accurate gauge of cultural accommodation. 

Culture interviews, therefore, are a must. Once you've established that a candidate dots their i's and crosses their t's as far as skills go, conduct another interview, but invite a trusted colleague along for the ride.

Your focus in this interview should be whether the candidate's attitude, personality, etc., will jive and thrive with what you've striven so hard to create. Having another set of eyes and ears around is invaluable to this process. 

2. Hold monthly company meetings.

There's an old saying that applies here: "The family that prays together, stays together." Whatever your opinion of its literal claim, its figurative one holds true.

Regular gatherings--when held by people who share a unique vision and mission--are enormously effective. They remind us of why we're on a particular journey and our reasons for trusting our companions.

They give us an opportunity to eat, learn and laugh together; to review our goals and acknowledge both our successes and shortcomings; to vocalize our future ambitions while reaffirming our commitment to being the best we can be today.

3. Host monthly happy hours.

My company has offices in California and Utah. Some of us drink and some of us don't. Lots of us like board games, while others prefer to sit back and shoot the breeze.

Individual inclinations aside, the simple act of shedding professional concerns for an hour and relaxing with one's colleagues does wonders for body and soul. Working and playing together go hand in hand.

Chips and salsa and beverages are a relatively cheap way to ease tension and foster friendships. Bonding is bonding, whether it's over something silly or serious. Besides, you haven't lived until you've seen 10 intelligent people scheming and screaming their heads off during a round of Secret Hitler.

4. Don't forget your one-on-ones.

A friend in therapy once told me that it was worth the expense just to have someone really listen to her for an hour. If that's true of a doctor-patient relationship, think of the implications for you and your employees.

We're all on this earth for a relatively short amount of time. We're here and then we're gone. Each of us has a deep, yearning need to express ourselves and have that expression acknowledged and validated by those we place our trust in.

If you want to build a company culture that'll last; if you want to gather a team that'll weather any storm; if, in short, you want to foster an environment where folks feel safe, happy, integral and motivated--keep up with your one-on-ones. 

Meet with your people face to face. Hear what's on their minds. Remember the names of their partners and children. Doing so is just another way of saying I love you. And it's corny as hell to write, but love makes all the difference. 

It makes the difference between a vibrant culture and an apathetic one. It makes the difference between inspiration and discouragement. Never underestimate the power of scheduling a few minutes to ask someone how they're doing. Never underestimate the power of listening to their answer.