Here is an excerpt from an article written by Penelope Trunk for BNET, The CBS Interactive Business Network. To check out an abundance of valuable resources and obtain a free subscription to one or more of the BNET newsletters, please click here.

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Your earning potential pretty much tops out at age 40. This is because your skills become increasingly valuable until you amass fifteen years’ experience, at which point you’ve hit a peak. According to statisticians at PayScale.com, in all fields except law, people are not paid more money for experience beyond fifteen years.

This means that to remain relevant and continue to increase your value, you are going to have to learn skills outside of your field. Here are five skills you should pick up as your earning power is due to drop.

[Actually, here are three. To read the complete article, please click here.]

1. Community building.

Yes, this is an irritating buzzword for social media mavens who are probably fresh out of college and run their whole life on Facebook and tumblr.  But the reality is, social media infiltrates everything, in the same way that email  became essential 10 years ago. Ninety percent of messages today are via social media link, according to The Pinnacle Group, a New York City think tank. Only ten percent are via email. So we are already at that tipping point where you need to learn social media or go home. People who are exceptional with social media can build a community around themselves in order to get jobs, promotions, and do good works for their company. Here’s a first step: How to start a blog.

2. Information processing.

Remember the term “information overload”? That went out of fashion when hipsters made productivity blogs one of the most popular genre of blogs, and time management books hit the New York Times bestseller list. Today you are in a knowledge market, where knowledge workers trade on their ability to synthesize information faster and in more collaborative ways – or faster and in ways that are so innovative that their ideas stand out above the rest. Information processing requires a clear understanding of one’s priorities, and an insatiable curiosity. Starting point: Time management tips for multitaskers.

3. Bridge building.

People who change jobs frequently build a wider set of skills and a wider network – both of which make them more employable. Job hopping enables you to create a series of bridges as you move between companies. The workplace no longer provides secure jobs, but you can provide security for yourself by creating a dynamic career where you move from job to job.  You can develop contacts and build relationships outside of a job, for sure, but if people don’t get the chance to work with you, then they can’t endorse your ability to work. Likewise, if you work in a company where people tend to job hop, you can still build this wide network providing you remain in touch with them after they move on.The best way to build a wide network is to actually work with a wide range of people.

Your resume, if you are doing this right, should reflect a significant, positive impact wherever you work, and you should leave in your wake a swarm of happy managers and co-workers who felt lucky to be on projects with you. That’s how strong the performance of a good job hopper is. Subset to this skill: How to quit a job.

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In general, it’s not about how old you are but how open you are to new ways of communicating. Aim to be open, widely networked, and adaptable to new ways of thinking. And in that vein, you should ask yourself routinely, what generation am I?

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Penelope Trunk is the founder of three startups, most recently Brazen Careerist, a professional social network for young people. Previously she worked in marketing at Fortune 500 companies including Mattel and Hyundai. Her blog about career advice, blog.penelopetrunk.com, receives half a million visits a month and is syndicated in more than 200 newspapers. She frequently appears as a workplace commentator on CNN, 20/20 and FOX News. She’s also the author of Brazen Careerist: The New Rules for Success, a bestselling career advice book for Generation Y.