Merlin Mann, the self-described "head basket case in charge of productivity on the Internet," started his presentation at Macworld Expo this week by thanking his sound engineer. He finished up by offering to share his Altoid mints with everyone in the audience. In between, he gave a funny and insightful talk on how to take control of your own time and attention.

Mann is a blogger at 43 Folders, which provides tips and discussion for people looking to maximize their productivity. He's been a main driver in the popularity of a self-help personal-productivity book and philosophy called, Getting Things Done, by Dave Allen.

Unlike other self-help programs, which try to make you more spiritually evolved, or change your entire focus on life, GTD's goals are more modest: It's a system of small steps to get your life organized, reduce stress, and prioritize the tasks you have to do -- from small things like taking out the trash to big things like starting a successful business.

"A lot of these motivational speaker guys with big teeth like to talk about capital letters like Values and Excellence. I don't even know what Excellence is," Mann told an audience of Macworld attendees. "But you can take measures to achieve modest goals, like getting home at a reasonable hour and not spending all weekend catching up on e-mail."

The key is to take charge of your own time and attention, Mann said. Don't be too quick to give other people the authority to boss you around, and don't take on habits like reading RSS feeds, fiddling with Facebook, or watching TiVo, if those habits aren't providing you with any value.

Sounds simple -- but most people don't really have a handle on how valuable their time is, Mann said. If a co-worker approached you in the hall and demanded $100, you'd give him the brush-off, because you know how valuable $100 is and you know what it feels like to lose $100. But the same co-worker can drag you into a meeting that wastes your time -- a resource that, like money, is precious and finite.

"When the value of your times is set too low, or not at all, it leads to waste and abuse," Mann said.

This is a particular problem for knowledge workers. (How do you identify knowledge workers? "Look for someone with girlie smooth hands who can go to lunch whenever they want," Mann explained.) Knowledge workers have huge amounts of freedom in how they work, they aren't micromanaged, they just have goals to achieve. That freedom is dangerous. "You can find yourself at two in the morning staring at Wikipedia covered in pizza crusts," Mann said.

Knowledge work jobs are "black box jobs," he said. If you're a knowledge worker, inputs go into you -- people give you specs, you go to meetings, you take in e-mail -- and the product comes out. You're the black box in the equation -- your colleagues and managers don't know how you work, and they don't want to know.

Moreover, knowledge workers have complex reporting relationships. "How many of you are doing exactly one job for one person?" he asked the audience.

Knowledge workers have a lot of dotted-line reports and relationships at work, and managing all those relationships is part of keeping the black box running. "Boss #7 does not care that boss #3 really wants something done," Mann said.

Decisions on where you allocate time in that matrix have opportunity costs -- if you're doing one thing, you miss an opportunity to do something else. He showed a photo from the set of the old TV show, Let's Make A Deal, to illustrate the point. "If you choose Door #2 you don't get to see what's behind Door #3, which is really a shame, because that's where the donkey is," he said. What's the answer? Use lifehacks -- little tricks for cutting through time-consuming problems.

And renegotiate -- start working with the people you're accountable to in order to waste everyone's time less. "There is a certain amount of attitude of victimhood that is inherent in knowledge work," Mann said. "As much as you want to blame your douchebag boss for your problems, you let a lot of stuff into your world" -- RSS feeds, YouTube, Netflix, and TiVo are all potential timesinks.

"Part of this renegotiation is understanding who gets access to you, understanding when they get access to you, and understanding how long they get access to you," Mann said. "If you're going to be a productivity ninja, you need to be able to make quick decisions on that."

Another potential timesink: E-mail. "You can tell a lot about someone by how they choose to spend their time," Mann said. "And you can tell an extraordinary amount about someone by who can demand their attention at any time, and get it." Most people give that kind of authority to e-mail -- whenever the e-mail dinger goes off, most people drop what they're doing and check e-mail.

Mann suggested turning off mail settings that have it poll automatically, instead setting e-mail checks to be manual. He also suggested turning off alert sounds that tell you when you have new e-mail.

He suggested simple e-mail filters to make the most important messages float to the top. Since he's been bombarded by press releases, he has a filter set up that deletes anything containing the words "For Immediate Release." And e-mail that's sent to multiple recipients "goes into a little gray folder I look at once a day," he said.

Another lifehack: Learn to qualify "yes." If someone asks you to do something, don't just say "yes," qualify the answer. Learn to use words like kinda, maybe, later, and a little. Say you're "kinda interested," ask for "a little more information," Mann said.

Knowledge workers can also start trying to change the culture in their companies to permit better productivity. Start with your own workgroup of immediate co-workers, Mann said. Get together and solve some small problems. Get people started using meaningful subject lines in e-mail. Get everybody to agree that e-mail should be used only for FYIs and messages that can be checked every day or two, IMs should be used for immediate problems, and if IM conversations go longer than a few minutes, they should switch to phone. Set times for "radio silence," when nobody talks to anybody else and everybody just works. Do the opposite: Set office hours, where the whole team sits in a meeting room and anybody who needs to talk to the team about something can walk in and talk to them.

Learn to phrase questions. Mann is the father of a newborn daughter, and he said he's looking forward to applying a child-raising tip he got from a friend. "The best way to get a kid to go to bed is don't ask them if they want to go to bed, ask them what color jammies they want to wear," Mann said. Make it easy for other people to say yes. Don't ask to set up a meeting -- suggest a date and time. He said when he worked as a waiter, a colleague told him a simple trick: Always nod. Mann demonstrated: "Did you enjoy your meal?" he said, smiling and nodding. "Do you want to order some cheesecake?" he said, smiling and nodding.

Budget time on timesinks like Twitter and Facebook. "You can say to yourself, 'Sometimes I can eat a bin of ice cream but I'm not going to eat a bin of ice cream every day,'" Mann said.