One of the primary goals of the Ancient Taoists was to achieve immortality. To achieve this end they developed many physical, chemical, dietary, meditative and ritualistic practises. As Chin Shi Huang Di (The Yellow Emperor) put it "These Taoist Immortals are all dead, and I am still here so much for their nostrums".
Were all their efforts of so little use that their discoveries should be consigned to the dustbin of history?
There is a saying "If you aim for the stars you may reach the moon". Which in this context means that although the target you have set your sights on is unattainable you may reach a lesser goal in the attempt. Thus in the endeavour to achieve immortality the Ancient Taoists achieved the goal of longevity, that is extending the capability of the mind and body to continue functioning properly until death.
This is a highly desirable result for us in the Modern day as our life expectancy has increased considerably (in the West anyway) and more people are spending many years suffering from mental and physical debilitation at the end of their lives.
Although a lot of what they did was dangerous and speculative some of what they discovered is still with us having withstood the test of time. Of these survivors are the callisthenic methods designed to strengthen the body, reduce tension and enhance the internal and external components of the body.
The Ancient Taoists believed that the lungs and heart had a predefined number of beats after which they would cease to function and the body would die. Thus to extend life one had to reduce the number of breaths and heartbeats to a minimum. Thus exercises were developed to slow down the breathing and heart rate. They discovered the best way to do this was to reduce the amount of work the body did when performing movements thus the body had to be relaxed and coordinated. They discovered that to be able to do this properly one had to be aware of how the body felt when moving and not allow the mind to wander aimlessly.
Perhaps the Ancient Taoists were not so foolish to aim for immortality. Even today prominent scientists and research institutes are investigating ways to increase the lifespan. Some even go as far as saying that ageing is a disease that can be cured. It is quite clear that the average lifespan has increased due to better diet, exercise, hygiene, lifestyle and medical practises . This is not so far removed from what the Ancient Taoists were doing but without the benefit of a huge body of scientific work to back it up.
Of course performing all these exercise routines ,preparing special meals and all the ancillary related tasks on a daily basis can be very time consuming so you may end up using all the extra time you have gained for yourself doing just this. So you may ask yourself what is the point of living forever if you have to spend most of the time either asleep or keeping yourself in shape so that you can live forever?