A) YOU are in charge.
50 years ago a career was like getting on a train. You were an accountant or a plumber and you'd be in this profession for 40 years. It was all very predictable and the tracks were fixed. In the 1970's it was like you were in a bus. During your working life you might have to transfer from bus to bus but there were established routes and roads. Today, having a career is like being in an all-purpose terrain vehicle and there are no roads.
YOU NEED TO BE THE DRIVER NOT TO SIT IN THE BACK SEAT !                                 
B)  Constantly do career research.                         
The amount of information in the world is currently doubling every 2.5 years. By 2025 it could be be doubling every week.
“The future belongs to those who are capable of being retrained again and again.”  From: Techo Trends  By Daniel Burns
“Ministry of Education figures show that enrolments in tertiary education among those aged 55-64 rose nearly 350% between 1999 and 2005. Enrolments of those over 65 went up more than 1000% from around 600 to more than 7000. Last year, students aged 40 comprised around a quarter of all enrollments.”   From Article: Things That Matter – The Listener (May 2008)
C) Pick an interest area rather than a specific job
“Frank Nuovo is one of the world’s best known indus trial designers. If you use a Nokia cell phone, chances are good Nuovo  helped design it. But as a younger man, Nuovo had a difficult time explaining his career choice to his family.”  Daniel H Pink.
“Your best option for a career in Sciences is to keep all your options open.” University Of Melbourne
D) Don’t pick what appears to be the easy, glamorous option
In 1965 a car mechanic needed to understand 5000 pages of service manuals. Now it is claimed that automotive engineers  need to decipher 465,000 pages of technical text   (250 big city phone books)
The typical business manager is said to read 1 million words a week.Yet in New Zealand today employers need to reskill existing employees, but cannot because of literacy issues. Most job growth in the world today is in high literacy skill areas
E) Use that brain of yours particularly during your formative teen years.
The number of thoughts, patterns a human brain is capable of making is: 1 followed by 10 million kilometres of 0’s. Your brain will never be full. In fact the brain is the only organ that expands through use.
In the early 1990’s Dr Jay Giedd of the US Institute Of Mental Health did MRI’s on the brains of 145 children, aged 4-21 and he noted an overproduction of grey matter during adolescence and therefore the inevitable pruning. “Those cells and connections that are used will survive and flourish. Those cells and connections that are not used will wither and die. So if a teen is doing music or sports or academics,those are the cells and connections that will be hard-wired. If they're lying on the couch or playing video games or MTV, those are the cells and connections that are going [to] survive.” Dr Jay Giedd

Think big and your deed will grow,
Think small and you’ll fall behind
Think that you can and you will,
It’s all in a state of mind.”
From: You Can If You Think You Can, By: Walter D Wintles