Logically, the query would seem to be: Why NOT grow a beard? But shaving is the norm and letting the beard produce is the exception. So, it may need a bit of courage to take the decision to grow a beard. Once that result is taken, it is easily reversed upon second thought. And another would-be beard disappear. When you see someone who has a full-grown beard, you know he made the decision to be bearded and he had the determination to stick by way of it and then you think how to grow beard.
Whether or not you should grow a beard depends in great part on genetics. Beard growth is genetically single-minded and there is not much someone can do other than to accept what they've been given. If you want to learn how to develop beard and have developed enough facial hair to let you to grow a beard, then you owe it to yourself to produce it out at least once during your lifetime -- even if only as an experiment. You may be so pleased with the results, even without warning so, that you decide to keep the body hair permanently.
Most importantly, the choice to grow, and subsequently keep, your beard is yours. The only estimation that matter is yours. So, go intended for it! If you like it, keep it. If not, then shave it off. At the very least you will have given it a try and you'll know what it was like to produce your beard.
Steps for how to grow beard
Stop shaving and let your facial hair grow for several days (or weeks) depending on how quickly your hair grow. Resist the urge to start determining it yet. (Usually about a month)
Once you have a appropriate length of facial hair, you'll see if you have the capability to actually grow a full beard (and if it suits you). Some guys just can't grow full beards and it doesn't suit everyone.
You can silhouette the hairline on your neck if you don't want hair extending all the way down your face. Avoid using the body hair as a replacement for a jawline, shave your neck, but not all the way up to the jawline. as an alternative, stop shaving about one inch before or use your beard trimmer to "fade" the beard absent as it grows down the neck.
For optimal beard preservation results, a beard trimmer with several length settings frequently works best.