Frigid offices. Summertime weather. Fantasy football leagues. What do these three things have in common? Studies say they all cause your productivity at work to plummet.

You cannot always control your environment, but you can control what you get done. And more than that, you can learn from others to be even more productive. Sure, there are simple ways to achieve more -- like finding the ideal room temperature or cutting out Monday Night Football.

But these are small hacks that will only do so much. There are more meaningful ways to be your best. And you can learn these skills by following the lead of some of the world's most successful people.

Here are four secrets for getting important work done, according to these billionaires and successful entrepreneurs:

1. Make room for big goals

Staying productive is about setting big goals and then taking serious steps to accomplish them. This is why Mark Zuckerberg makes room each year for a new challenge, saying he wants to "learn new things and grow outside my work at Facebook." To date, he has done everything from learning Mandarin to meeting a new person each day outside of work -- big goals that fit into his overall vision for work and life.

Amazon's Jeff Bezos takes a backward approach to this goal-oriented thinking -- literally. He makes room for big goals by starting with the customer's needs and working backward to build skills to get that work done faster. Says Bezos, "We learn whatever skills we need to service the customer. We build whatever technology we need to service the customer."

2. Give each day a job or theme

The way you structure your day can either hurt or help your productivity. When CEO Jack Dorsey was splitting his time between Square and Twitter, he stayed productive by giving each day a theme -- Mondays for management, Tuesdays for product, etc. As he explains, "There is interruption all the time, but I can quickly deal with an interruption and then know that it's Tuesday, I have product meetings, and I need to focus on product stuff."

Then there are the "no-meeting Wednesdays" adopted by Dustin Moskovitz. The Facebook co-founder and Asana CEO believes that the mandate gives him and his team a solid amount of time each week for "focused, heads-down work."

3. Set limits for tasks, emails, and meetings

Wasted time and fewer results -- no time for that. Successful folks know how to make the most out of every minute and meeting. For example, businessman and former Nissan CEO Carlos Ghosn sets time limits on single-purpose, non-operational meetings. "The maximum is one hour and 30 minutes. Fifty percent of the time is for the presentation, 50 percent is for discussion."

Sheryl Sandberg sets another kind of limit -- the length of her emails. The Facebook COO and author says she responds to every single work email, but she saves time by keeping the responses short. "I would rather give a short, quick, incomplete answer than wait and do it better," she says.

4. Establish "deep work" zones

Focus, focus, focus. This is the final and perhaps most important productivity secret. Take Bill Gates, for example. In his 20s, he adopted a productivity technique called "deep work." And so he would set aside stretches of time each week to do his most challenging work without any distractions -- no stopping, not even for sleep. Author Cal Newport, who wrote a book titled Deep Work, has said, "Deep work is important ... not because distraction is evil, but because it enabled Bill Gates to start a billion-dollar industry in less than a semester."

You might try all four approaches. Or chip away, one tip at a time. The point is, these productive billionaires focus on doing a few things really well each day -- not a hundred things haphazardly.

And that might be the ultimate productivity secret: focus. When you bring more and more of it into your life, you might be amazed at what you can accomplish in a single day.

What are your productivity secrets?