The sixth house often get short shrift because its significations are generally mundane. However, the sixth house is more important in any other house because these mundane things are the very fabric of every day life, the substance and grounding on which all grand intentions must be rooted.
Consider the first meaning that astrologers assign to the sixth house: work. Most adults are gainfully employed, and even though we spend much of our waking hours engaged in work, it is ironically the thing people want to avoid the most. Everyone fantasizes about not having to work, or if that is not possible, then at least conjure up a dream job that would make them happy. The truth of the matter is most of us have to work to pay the bills, and most of us are “practical” enough that the dream job is just that, a dream that can’t be attained (so we think), given our skills, education, connections, etc.
And that is exactly why the 6th house is so important, because it gives us all kinds of clues about what kind of work environment would be most suitable for us. It is important to understand that the 6th house doesn’t by itself tell us what kind of career would be ideal (that involves a host of additional horoscope factors including the 10th house, the ruler of the 10th, aspects made to the MC, etc.), but having an insight into the work environment, and an understanding of what kind of day-to-day activity we might enjoy gives us a good sense of what kind of job (if not career) would be most suitable.
For instance, if you have Aquarius on the 6th house cusp of your horoscope, you would need a lot more freedom to set your hours than someone with Capricorn on the 6th house cusp. Or, you might enjoy doing night shifts (Aquarian sense of bucking the norm) which then puts you on a path to a different kind of job than most others. If you have Moon in the 6th house, you will likely enjoy working from home a lot (all things being equal), or have a job that brings you in contact with the public day in and day out (e.g customer service) because the Moon’s significations include home and the public.
Considering the natural sixth house, the corresponding (sixth) sign is Virgo, which contributes the signification of service. If you have an emphasized 6th house (containing one or more planets, especially the Moon, and/or ruler of 6th in aspect with many planets), you may enjoy any job that is about serving people: whether this is working in a restaurant (especially with Cancer on the cusp, since Cancer is about feeding), teaching, working as a nurse (which brings in the health dimension, more on that in a bit), working in a beauty salon (especially if the 6th house has Venus, or the sign of Taurus/Libra on the cusp), and so forth. A sixth house job often means finding joy and meaning in serving other people’s needs. In a deeper sense, there is a significant need to be needed, which is also often true of people whose horoscopes have the Sun or Moon in Virgo.
Another very important signification of the 6th house is health. I will make an important distinction here, which is often not drawn finely enough. The 6th house is about wellness, while the opposite 12th house is about illness – two sides of the health coin. The onset of serious illness if often seen from the 12th house, not the 6th, and this is also because the 12th house signifies hospitals (being confined to a hospital means retiring from worldly activities which is a 12th house thing, see the post on houses for an explanation). If you have an emphasized 6th house you may well be a health nut, with an outsized concern about your diet and your exercise. You constantly watch what you eat, and you always find ways to stay fit. Medical doctors (and psychologists) often have an emphasized 6th house for the obvious reason that their job is to keep their patients healthy, whether physically or mentally.
One of the 6th house significations that often gets forgotten is that of skill or craft, which actually arises out of the correspondence with Virgo. Like many Virgoans, people with an emphasized 6th house often work hard to develop a skill or craft that could be a big part of their daily work, or side venture, or serious hobby. A skill is something that is learned by doing, and requires much practice to hone into a craft. The skill might have to do with working with the hands (e.g. carpentry, knitting, handicraft), working with ideas (programming, writing, accounting), or other forms (sound engineering, playing a musical instrument). In all cases, there is a deep immersion in the work at a very detailed level, and a driving energy to perfect the end result.
There is another original signification of the 6th house, which is pets. I find this signification to be less than useful in a delineation of the personality (after all, many many people have pets), but it is found to be useful in predictive and horary astrology (e.g. my dog ran away, will she be found?)
Take a look at the 6th house in your horoscope: see the sign on the cusp, and the planets in the house. Use the cusp sign to understand how you approach your work and work environment in general. Use the planets in the house, if any, to understand and acknowledge the special emphasis that is placed on work, health, and skills. About skills, if you have a heavy emphasis on the 6th house, you are likely called on to specialize in a very particular line of work, with the goal of attaining mastery in it.