"Pneuma", "Ojas", "Qi" - these are all just ways various cultures have conceptualized and named the vital life force that animates and invigorates your body. It is the spark of life that runs all of your organs, brings consciousness, drives and directs growth and development, protects you from illness and, when it leaves brings death.
In Chinese medicine, they speak of "prenatal" and "postnatal" life force. Prenatal Qi is the spark of energy your parents gave you. It is the energy that started your cell division, carries your genetic code (constitution), oversaw (and oversees) proper developmental stages, and is the core of your vitality. You cannot get any more and when you run out you die. Every day you lose a little more. How much depends on how you live your life. Excessive lifestyles, "burning the candle at both ends" and unhealthy diets and habits all consume prenatal qi at a rapid rate. Thus, all Chinese longevity strategies are ways to conserve prenatal qi.
Postnatal Qi is the energy you bring into your body after you are born. Ideally, you want to have lots of postnatal qi so that your body uses more of that than prenatal qi while living life. By having a lot of good postnatal qi, you can create a bit of a buffer zone to protect your prenatal qi.
Postnatal life force comes from two main sources plus a number of lesser sources. The two main sources are: respiration and digestion/ absorption. That is, the air we breathe and the food we eat. The healthier we do both, the better we will be.
However, when one of those starts to lag - then issues arise and begin to spiral. For example, asthma might decrease one's "Kong Qi" (respiration energy). This will make the body's overall amount of energy less and thus, like a fire with too little air, it will begin to run inefficiently. Over time, digestion will become sluggish too compounding the problem. Conversely, digestive problems to begin with will mean that the organs are not getting the nourishment they need to replace and rebuild themselves. Over time, the lungs will become weaker and respiratory problems will arise. There are many remedies in traditional medicines including herbs, acupuncture, qi gong, and some kinds of bodywork designed to address both of these issues. Once you get one system working better, the spiral reverses and the other system will eventually improve as well.
Where the problem gets sticky is when prenatal qi is involved. When a person's prenatal qi has begun to wane due to age, illness, lifestyle or accident that also brings down their overall amount of "operating energy". All of their systems begin to function less effectively so that they cannot create that buffer of postnatal qi. Traditional remedies can optimize those systems but without the underlying prenatal qi which cannot be replaced, they will continue to be impaired.
This is where the "lesser sources" of postnatal qi become important. These sources do not use the respiratory or digestive systems. These are the qi one absorbs from people and things we come in contact with, from energy work such as Reiki, and from the Divine (however you envision It/Him/Her/Them). Prayer and feeling the Divine energy enveloping and filling you. Or carrying energetically charged stones, crystals, knotted ropes, amulets and talismans. Drinking energetically charged gem waters. Shamanic journeys to regain lost parts of oneself. Drawing on the energies of Nature, be they lunar, solar, the power of a river, or the strength of the earth. There are many, many of these lesser sources. None of them will substitute for food and air, but in many cases they can add just enough to make up for the low prenatal qi.
Working with these lesser sources can be tricky because each energy source/ technique will have different energetic qualities that need to be catered specifically for each person. The wrong source may add energy but cause harm in a different way. However, with proper guidance and education from someone who can accurately diagnose and assess a person's qi and energetic imbalances, people with low prenatal qi - including the elderly or very sick - can often at least stop the downward spiral if not reverse it.