Taking vocal lessons as an adult may have added obstacles that younger students don't encounter. In order to work through these impediments, it is important to first recognize what they are. In addition, if you ensure that your vocal lessons are as enjoyable as possible, you will find yourself even more motivated to make the required effort.
One problem that most adults face when they want to take vocal lessons is how to find the time to fit it into their schedules. With work, family, hobbies, home life, and maybe even school or other classes, it can be really difficult to carve out the time needed to focus on your voice. If you want to work through this, you may need to choose vocal lessons over some other activity. Look at your schedule and see what things you might be able to remove in order to free up the time necessary for your lessons.
Many adults are also more intimidated by the idea of vocal lessons than teens or younger children. Children seem to just naturally be less self conscious than adults are, so it may take some extra internal pep talks to convince yourself that you can do it. In most cases, getting yourself to the first couple of lessons will be the hardest part. Once you discover how much fun they are or start to recognize your own improvement, you may find that you start to really look forward to your next one.
Sometimes adults just aren't interested in some of the basics that are taught in typical vocal lessons. Instead of finding yourself singing "Hot Cross Buns" for the next several weeks, seek out an instructor or a program that allows you to learn the things you want to learn. Do you love R&B? If so, find a program that will prepare you to sing those types of songs.
Of course, everyone has to start with the basics, but if you are able to move on to the kinds of songs that you find more enjoyable, you're going to have more fun. More fun means that you'll want to stick with your vocal lessons. Not only that, but if you're learning to sing the music you enjoy, then you're more likely to use the skills you've worked so hard to attain through those lessons.