There is never an age when you should stop learning. You may have gone through high school and college and started your career, but that does not mean that you are done learning new things. In fact, you should try to learn until the day that you die. One thing that can help you learn more and that can also improve your life and your career is to improve your vocabulary. There are a quite a few ways that you can go about this, and you can do it alone or with a few friends if you wish. It's not hard either.
One thing you can do is to use a highlighter the next time you read a book (just make sure it is one that you own not one from the library) and highlight any words you don't quite understand. You can often get a slight understanding of a word though usage, but there are words you may have read your whole life without an understanding of what they really mean. When you are done with the book, you can go through and look them all up, and then try to use them in your day to day life. If you never understood the true meaning of tryst you may have a hard time using it from here on out, but at least you now know the true and correctly definition.
Some people like to flip open a dictionary to a random page and then skim through for a word they do not know. You too can do this to improve your vocabulary. This could be a word they have heard before or one that is completely new to them. They then study the word and try to use it in their daily conversations for a week until they feel they have a full grasp of the word, when it is appropriate, and they can also see how many other people use the word. A never-used word won't do much good, but it can always be fun to learn about it.
There are ways you can learn new words and improve your vocabulary that may take more time, but they are very useful and work very well. Look online for college level vocabulary lessons. You won't always find these for free, but you can at times. These should be full of words that are not used often, or full of words that are often miss-used and misunderstood. You may even find lists of vocabulary words that pertain to your life or your career, which can help you at work. You can also find general business words, technology words, or even lists of ancient words that are no longer used but that help you with base words and phrases that you can learn in other languages.
You can improve your vocabulary the old fashioned way as well. You can take some writing or English classes either online or at your local community college. You have to pay for these, of course, but they can not only help you improve your vocabulary, they can also give you a stronger written voice and a better understanding of how to communicate via the written word, which will help you in all aspects of life, and also may make you more useful and valuable at your job.