The working environment these days is insecure, and there is no such thing as a job for life any more. While some careers are far more secure than others, such as a profession with rare skills like veterinary surgeon or doctor, generally speaking you should not expect to go into a job for life when you leave college or university. You may not even get the type of job you want in the career that you want.
When you start to think about career training, it is probably in your interests to be prepared for alternative careers, or maybe careers that can be moved from one industry to another. If you set off on a single track and that route hits a dead end, then you may struggle to redirect yourself into another career.
Precisely how you go about dual career training is going to depend on what your first choice career is, and the types of skills that are required for that career.
I will use my own example and hope that it may give you some ideas for your own situation. As a teenager I presumed I would make a living from writing, but I was realistic enough to realise that that would not happen overnight, so started working in offices at 18, in order to save money for travelling and take off 6 months at a time to write.
I soon realised, back in 1970, that there were two skills that would become increasingly important across a wide range of jobs: finance and computing. With writing in the background, I focused on developing finance and computing skills, and always keep up with developments.
As it turned out, like many who aspire to writing, I made no living from that whatsoever; although today, 36 years later, I do. In the meantime, I have metamorphosed through computer systems analysis, computer system testing, qualifying as a management accountant and into project management where all those skills were used. I was able to move from one project to another quite different type of project without too much of a problem. All of that set me up with the business skills and confidence to have my own business in the UK.
Looking back, it was important that I kept developing a range of skills and was flexible about moving between jobs and disciplines. I had several career changes along the way, but all built on that original decision to develop skills in finance and computing. All that led to being able to take an occupational pension early, at 50, and carve out a new living online and writing from my dream location, a tropical island in the Philippines.
Your situation, aims and ambitions will be very different to mine, but I do believe there are some lessons to be learnt from the way my "careers" have run into each other and from each other. From examining your own experiences, training and ambitions, you may well be able to spot some ways you can better prepare yourself for dual careers or career changes. There could come a day when that is critical.