There is an unfortunate temptation if you have been in the same company and the same job for a while to stop pushing yourself to learn something new. Your job may not require it. Your boss may not want to pay for it. All your colleagues think you are great. Your reviews are great. So why spend your own money on professional development?
Because no job is secure, and no company is secure, as this recession has shown us, again. Because learning something new will energize you and boost your confidence. If you are in marketing and you don't know how to use the social media, your career is limited. If you are in human resources and you don't know the latest about FMLA, you are behind the times. If you are in finance and you don't know the latest in FASBs, you may actually seem out of date. Just the way you seem out of date if you are still wearing what you wore in your college days.
If you don't update your wardrobe and your technical skills in your chosen field, you will be left behind. So, join that professional organization you think is so great, whether or not your company pays for it. Take that course or class you think will really help you. Spend your own money, if you must. Invest in your career. It is always worth it.