It takes about 6,400 hours of class time and studying to get a 4-year degree. Assume that it takes you only 5,000 hours to master your field.
While you are happy that you've prepared for your profession, the knowledge you've learned is fast becoming outdated. We can safely assume that in 10 years, 50% of the facts in the field would be outdated. This means that for you, just to keep up in your current field, you'd need to learn 5 hours per week, 50 weeks a year.

The Simple Math 

When we consider the future of work, there are two trends we should keep a note of. They are:
<ol>
<li>Half-life of knowledge</li>
<li>Law of increasing learning</li>
</ol>

Trends To Consider

Informal learning outside of traditional institutions accounts for 70 to 90 percent of all learning. 
If other people are learning more, then you have to learn just as much to stay relevant. If you don't, you will fall behind. If you are in your current job, you might not even realize how far you're falling behind. It might only become apparent if you try to transition to a new field or re-enter the market after a break.

The law of increasing learning

Just as we have minimum recommended dosages of vitamins and minutes of exercise for maintaining physical health, we should understand that we also have to be rigorous about the minimum dose of deliberate learning that will maintain our economic health.
Those who do not keep learning will be left behind, stuck in a job, or unemployed.

Intellectual complacency

The most successful, busy people in the world dedicate at least 5 hours a week to deliberate learning.
The 5-Hour Rule is the most critical practice we can all adopt for long-term career success. However, almost no-one takes it as seriously as they should.

The 5-Hour Rule

The rate at which knowledge is becoming outdated is predictable and growing exponentially. For example:
<ul>
<li>Two surgeons found that half of the facts in surgery become false every 45 years.</li>
<li>In the 1980s, bacon, butter, and eggs were three of the worst foods you could eat for your heart. Now, many argue they are healthy.</li>
<li>Artificial intelligence, app development, social media management, YouTube content creation, and online course creation barely existed fifteen years ago.</li>
<li>Entrepreneurship classes taught to spend hundreds of hours creating in-depth, heavily researched business plans. Now, they are taught NOT to do business plans, but to focus on talking to customers and using lean startup principles.</li>
<li>We forget nearly everything we are exposed to over time without reinforcement.</li></ul>

Outdated knowledge

You might not think you have five extra hours in the week, but you do. The simplest way is to stack learning on top of your current schedule. Areas where you can leverage double-time every day:<ul><li>Driving to and from work</li><li>Exercise</li><li>Socializing (friends can learn together and talk about it)</li><li>Eating and food prep</li><li>Doing housework or yard work.</li></ul>With smartphones and the explosion of videos, podcasts, and audiobooks, you can learn while you do other things throughout your day.

A hack to double your learning time

Three years ago, I coined the term The 5-Hour Rule after researching the most successful, busy people in the world and finding that they shared a pattern: They devoted at least 5 hours a week to deliberate learning. Since then, I've preached The 5-Hour Rule to more than 10 million readers.