It's hard to say what exactly disease is. The
easiest way to define it is perhaps to say that disease is the
condition of not being well. Likewise, it is hard to say what it is
to ”be well”. Furthermore, feeling well or ill is a very
individual thing.
Varying pain thresholds
Imagine two women: Mrs. Hansen and Mrs. Petersen.
Having had a slight pain in the lower back for a couple of days, Mrs.
Hansen feels ill and seeks medical assistance. Mrs. Petersen, on the
other hand, does not feel ill or seek medical assistance until she
has had strong back pains for at least two weeks. Which woman is the
sicker? Mrs. Hansen, who feels the most ill, or Mrs. Petersen, who is
in the most pain? It is not an easy question to answer.

How the individual patient presents his or her health
issues to doctors also varies greatly. Some patients present their
doctors with very clear-cut and well-defined issues, that are easy
for the doctor to relate to. Others present very complex issues, that
may be a conglomerate of family-related, work-related, social, and
psychological problems.
Doctor's opinion
In the latter of the above
cases, it is important that doctor and patient reach a consensus
regarding the health of the patient, and work out how to interpret
the various symptoms. Some of the most common and well-defined health
issues that patients bring to their doctors are: coughing, back
pains, fever, headache, and fatigue (see below). It is up to the
doctor to correlate the symptoms and other relevant circumstances in
the patient's background, and assess whether the cause of the
symptoms is disease, and, if so, how to treat it.
Coughing
Coughing may signal both passing illness, such as
common cold, and graver diseases in the lungs and heart. However, it
is important to remember, that couging is a perfectly ordinary thing.
Coughing is an air current generated by the body in order to banish
phlegm and foreign bodies oyut of the airways. Respiratory diseases
may also cause coughing. It is not abnormal to be coughing for
prolonged periods – weeks, even – and in such cases, you should
seek the advice of a doctor.
Back pains
Back pain is a very common complaint. Pains in the
lower back (lumbar area) are particularly common. These are often
caused by over-exertion, or by incorrect working posture. A number of
people develop these types of back problems easily because their back
is in poor shape from lack of bodily exercise and normal physical
activity. If the pains in your back radiate down into your legs (and
you perhaps also have problems with incontinence), it is imperative
that you seek out the advice of your doctor, as you could suffer from
spinal disc herniation.
Fever
Normal body temperature is around 37°C
(98.6°F). Body temperature is lowest in the morning, at around
36.5°C (97.7°F), and gradually rises during the course of the day.
If the body is infected, it is common for the temperature to rise. If
the temperature rises above 38°C (100.4°F), we are said to have a
fever. However, the gravity of the illness is not so much determined
by your temperature, as by your general condition and well-being. You
may feel perfectly fine, but still run a fever. Similarly, you may
feel ill and have no fever. If you have a fever, it is important to
drink abundantly, as your body will consume more liquid than normal.
Headache
Headache can have
many causes. The vast majority of people experience headaches from
time to time, without otherwise feeling ill. Even if you don't feel
ill, headaches can be very bothersome. It may affect your mood,
energy, level of physical activity, and your social life. If you have
headaches often, you may suffer from migraine, which can be extremely
severe and may be accompanied by visual disorders. Headaches may also
be caused by muscular tension in the neck and upper back, which
spread into the skull in the form of headaches.
Fatigue
Everybody occasionally feels fatigued, and the most common cause is, naturally, lack of sleep. But there are a whole range of reasons other than lack of sleep why one may feel fatigued. Fatigue may be a sign of disease or illness, though it is important to remember that fatigue is not in and of itself a symptom of disease. It is perfectly normal to feel
fatigued for brief, or even longer, periods of time in connection
with certain common diseases such as common cold, flu, or stomach
flu. A common cause of fatigue for menstruating women is iron
deficiency. An unhealthy life style may also be the cause of fatigue.
Unhealthy food, inadequate liquid consumption, too many cigarettes
and too much alcohol, and lack of sleep may all cause, or contribute
to, fatigue. Lastly, it should be mentioned that you may also feel
fatigued if you are stressed out, depressed, or feel sad in general.