A general lack of energy is a common problem in spiritual practice. If a person feels weak or ill, he has no power to change himself. To walk the path, you need energy and lots of it. Any spiritual practice or meditation may significantly drain the practitioner.
It's a question of energy balance, just like the balance of a banking account. Any person consists of energy by default, so the deficit of energy is caused not by the lack of energy production but rather by the excessive expenditure of it. There are many active and energetic people that don't know anything about the lack of energy or even the notion of human chi, but they feel alive and well. But their lifestyle gives them a power bonus, whether they do it consciously or not.
Sometimes, lack of energy has to do with Manipura chakra. Stress and anxiety disturb digestive organs, translate into poor energy balance, and reduce a person's willpower to do anything productive. Then, it leads to a vicious cycle of doing nothing and feeding bad emotions. The only solution then would be to pick yourself up and get out of this mess forcibly.
Usually, if a person feels lazy, tired, or sleepy for extended periods and only wants to eat, sleep, and be passive, it's a bad sign. While a couch potato sits and does nothing, an active person works hard without the sign of tiredness. But what does separate the two? It may be illogical, but the lack of energy results from the person's passive lifestyle. An average day is low on events and emotions that may lead to a depressive state, and it means low energy in the emotional body of Anahata-charka.
When we are talking about lack of energy with regard to spiritual development, it's important to clarify the type of energy we are talking about. Many people, when feeling low energy, think the problem is in their bodies, but in many cases, low energy is not a consequence of some disease but a low state of mind. A person may appear healthy but constantly feels tired and empty, even though they didn't do any hard physical labor. So the problem is in mind, in the negative emotions and thoughts that drain energy. In many cases, this leads to apathy, being introverted and not outgoing.
People may regard this as a part of their personality and be proud of their solitude, but in reality, it's their ego that drains them. When low on energy, a person becomes self-centered, pessimistic, dark, and insecure; he (she) becomes a yin-object. Other people see this and avoid communication with this person because they naturally feel how their energy drains toward that person, and nobody likes to feel down. It leads to a vicious circle; people with low energy feel others abandon them in the sense "nobody likes them," and they lose joy in life.
Distraction and absentmindedness may also be a symptom of low energy in the conscious. Some people daydream a lot, and they often find themselves in their fantasies and illusions. However, any thought or illusion may materialize in the future, so we deal here with people's inclination to the Air element, which involves active When is Air element is most active in the conscious, the energy levels get lower because the metrics of space connected with Air element has lower energy density, there is more vacuum. The outside pressure of a realm is lower, and the person loses more energy into space until there's a lower equilibrium point. Mages are taught to find energy sources there, but they are not ordinary people. Daydreamers usually lack power and are more talkers than doers, but this low energy is a state of mind, and no forceful ways, like physical exercise like morning jogging, can fix this. Yes, physical exercise is an action of "now" and forces a mind out of thinking into reality, but the problem is that the mind will return to its original state sooner or later. Therefore, new year's resolutions usually don't last, and the jogging will end quickly.
Sometimes tiredness and lack of energy come from a problem with the physical body. When a person leads a sedentary lifestyle, the chemical and energy processes in the body slow down, and the conscious gets less energy from the body. A person may have a chronic issue, and the energy supply will decrease because the body is fighting the disease. If there's a problem with the body, physical exercise may help. Higher muscle tone increases blood circulation and reduces stagnant processes like low metabolism.
More often than not, people begin to lack energy when they discover spiritual development and start learning the occult. This is a great work that is unseen to the eye but requires a great deal of energy. Someone strives to achieve a higher state of mind and to "increase vibrations," but the price for this is very high; recovery from one state may take weeks. It happens especially when you train improperly or without guidance. It's easy to find exercises online, but there will be missing details, such as exact mechanics, how long to do it, and frequency. Because of missing information, the same exercise can do more harm than good.
Many people spend years trying to achieve some higher state, but all in vain because they do it wrong, like trying to drive a car without gas. A practitioner also needs to remember that any magical experience takes a toll on health and the immune system. That is the reason a magical practice should be exercised in a cheerful mood and should be limited so that consciousness is not overstrained. Mages first learn techniques of finding energy sources, so unprepared conscious should not attempt to do any magical work.