Commit to reading more books that you enjoy. Not only will reading help improve your vocabulary, but it can also open new worlds to you, new frames of thought. Books even help you understand people and the world better. These are all beneficial. When you lack words, you shut down new insights and lines of reasoning.
Sign up to an e-mail service with a word of the day or purchase a word of the day calendar. Try to use the new words you learn in sentences and get used to their sounds and appearances. "The difference between the right word and the almost right word is the difference between lightning and a lightning bug" - Mark Twain.
Try to absorb intriguing new words you come across. Learn their meanings so that you can throw them around in your everyday speech. Let them simmer in your mind.
Set a goal to learn one new word a day or if that's too much for you, set a goal to learn one new word a week. You can never put a price on a great vocabulary and excellent communication skills. You can only increase your marketability! Each new word you learn opens a new avenue of thought, enpowering you to think or take action in ways you never have before!