If the 20th-century career was a ladder that we climbed from one predictable rung to the next, the 21st-century career is more like a broad rock face that we are all free climbing. There's no defined route, and we must use our own ingenuity, training, and strength to rise to the top. We must make our own luck. The lightning-fast evolution of technology means that jobs can now become indispensable or outmoded in a matter of years, or even months. Who knew what a "Community Manager" was ten years ago? What about an "iPad App Designer"? Or what about "Chief Scientist" (at LinkedIn)? A substantive portion of the working population now earns its livelihood doing a job that didn't exist 10 or 20 years ago. And if your job itself hasn't changed, chances are you're using new and unanticipated technology and/or skills to perform that job. (E.g. You're a designer who blogs, a comedian who uses Twitter, or a branding consultant turned e-tailer.) Ten years from now, we'll probably all be doing some new type of work that we couldn't even possibly imagine today. The thought is both exhilarating and frightening. How do we prepare for a future filled with uncertainty?

1. Explore, relentlessly. The tools you use today will not be the tools you use in the future.

You may have heard the term "life sport" before. It refers to sports - like golf, tennis, or swimming - that you can play from ages 7 to 70. The ever-brilliant Kevin Kelly recently expanded this concept to include technology as life sport, outlining a must-read list of "techno life skills" that we should all cultivate. As Kelly puts it: "If you are in school today the technologies you will use as an adult tomorrow have not been invented yet. Therefore, the life skill you need most is not the mastery of specific technologies, but mastery of the technium as a whole - how technology in general works." Whether it's interviewing someone over Skype, developing an affable Twitter persona, learning how to publish an e-Book, or experimenting with a new task management app, we must become adept at testing out new technologies that can benefit us in our personal and professional lives. Sometimes, we will choose NOT to integrate a new technology into our lives, and that's okay. It's the experimentation, and the awareness that we gain through it, that's key.

2. Recognize like-minded friends and peers, and cultivate those alliances.

Technology will never change some things, and one of those is the power of relationships. As Ben Casnocha, co-author of The Startup of You recently told me, "Opportunities do not float like clouds in the sky. They're attached to people. If you're looking for an opportunity, you're really looking for a person." Work, knowledge, and opportunities flow through people, which means that who we know - and how we know them - is our most important asset. But relationships don't get built by exchanging business cards. They get built with energy, care, enthusiasm, and, most importantly, time - lots of time. Ten years ago I worked at a publishing startup, and I still know at least 10 people from that job, who have gone on to become creative directors at a global design agencies, architects at cutting-edge firms, lead product developers at digital music labels, fashion entrepreneurs and editors, social media gurus, and the list goes on. You never know where people will end up.

3. Help people whenever you can. Don't expect anything in return.

We can all be pretty sure we're going to need help at some point in the future. As leadership expert and ethnographer Simon Sinek articulated in a rousing 99U talk, "We're not good at everything, we're not good by ourselves." Sinek goes on to describe how the ability to build relationships is the key to our survival as a race and to thriving as idea-makers. The number one way to build relationships, of course, is by helping each other. But in an age of complex connections and contingencies, there isn't always a simple 1-to-1 correlation between acts of generosity. (As in, "I'll scratch your back, you scratch mine.") And there shouldn't be. Helping our peers, colleagues, and allies should be a regular habit and its own reward. We usually can't foresee how, but the goodness always comes back around.

4. Keep learning - on the job, and off.

If you want to stay at the top of your career game, indulging your curiosity is your greatest asset. It could mean attending conferences or lectures relevant to your current occupation, or spending an hour every weekend on Code Academy, or finding an excuse to interview the people you admire most.With resources like Coursera, EdX, Khan Academy, Skillshare, General Assembly, Lynda.com, and more, there's no excuse not to expand your knowledge. If you can create something tangible that you can show a potential employer in the process (e.g. a writing sample, a portfolio piece, a website, etc), even better.

5. Be proactive about proposing new roles and tasks.

The days of "grooming" young employees for senior positions are over. No one is going to spend more time thinking about your career than you are. (And, honestly, why would you expect them to?) As NY Times op-ed columnist Thomas Friedman writes, employers "are all looking for the same kind of people - people who not only have the critical thinking skills to do the value-adding jobs that technology can't, but also people who can invent, adapt and reinvent their jobs every day, in a market that changes faster than ever." You won't be rewarded with exciting new opportunities by keeping your head down and following the rules. If you want a new challenge at work or more responsibility, it's on you to pitch your boss or your client on what needs to be done, why it's a good idea, why you're the best person, and why everyone will benefit. Lead the way with your own creativity and initiative, and back it up with enthusiasm and a strong business case.

6. Always be asking "What's next?"

If you're not asking questions, you're not going to find answers. And we often wait to ask those hard career questions right up until the very moment when we direly need answers. We wait until we get laid off to think about what's next. Or we wait until we're completely miserable and burnt out at our jobs before we ask, "what's next?".But if you're going to switch jobs every four years or less, you should probably be asking yourself "what's next?" all of the time. I'm not talking about asking "what's next?" in a way that disengages you from your current job. I'm talking about asking in a way that helps you push yourself. Asking in a way that helps you hone in on your passion. Asking in a way that helps you decide what new skills you want to develop. Asking in a way that helps you reach out to meet that new mentor. Asking in a way that helps you take on that big new project at work that kind of scares you. Asking because if you don't ask, you'll never find out. -- What's Next For You? How are you preparing for rapid-pace career changes? What questions are you asking? Share your tips in the comments.