The purpose of sweat is to cool the body by sitting on the surface of the skin and allowing heat to escape from the body. Effective sweating is when someone is glistening as the moisture forms a cooling film over the skin. When sweat reaches the 'dripping' stage the body is struggling to effectively control the body temperature and will be less effective at cooling the body down. Whether someone glistens or drips, however, is not indicative of how hard they are working, it merely indicates how effectively they sweat. Factors such as the humidity and temperature of the environment you are working in and the clothing worn also have a significant effect on sweat production.
Work rate and sweating do not correlate together accurately, especially if you are getting back into exercise after a long period of inactivity. If you are starting aerobic exercise again after time away then you can sweat even if you aren't working particularly hard because it takes time for your sweating mechanisms to adapt to the workout.
As you exercise aerobically for a consistent period of time, you will start to sweat 'better' and will not drip as much at the same intensity of exercise. As well as this, the sweat becomes more dilute as you improve your sweating system.
Instead of taking sweating as an indicator of your exercise intensity levels, try using the Borg scale to measure your intensity levels. It gives a much more subjective indicator of effort because the feeling of fatigue is very highly correlated with heart rate. As you exercise, rate yourself between 6 and 20. If you can work hard enough to rate yourself between 12 and16 then you would be achieving the heart rate zone of 65-75% of your maximum heart rate:
6, 7 - very, very light exertion
8, 9 - very light exertion
10, 11 - fairly light exertion
12, 13 - fairly hard exertion
14, 15 - hard exertion
16, 17 - very hard exertion
18, 19, 20 - very, very hard exertion
Using such a scale would allow you to rate what intensity you are working at so you are aware of your training level.
Remember that there are many extremely fit individuals sweat A LOT, regardless of exercise intensity or duration. This relates to their glands rather than their fitness, and is another reason why sweating proves to be an inaccurate measure of work rate.
Nutritionist Emma Brown (ANutr), MSc Human Nutrition is passionate about how food science applies to the human body, and how the nutrients in what we eat affect us and ultimately have an impact on our health.