Magical energy and physical energy are the same thing: Energy.
I learned and practice a modified Triple Burner approach. Basically:
You have three energy centers (dan tians) in your body. One just below the diaphragm, one in the chest, one in the pineal gland. The lowest holds base energy (jing - "vitality"), the middle holds refined energy (shen - "spirit"), the upper holds ultra-refined energy (chi/ki - "manifesting energy", this one's more difficult to translate).
Most of your jing comes from your last life, post-natal jing can be collected through things like sungazing at dawn, but this collects small amounts compared to the reserve you come into life with. Some jing can be reabsorbed in daily life, as you use your energy throughout the day, pull it back into your body with your breath while maintaining good posture. Some jing can be reabsorbed in the process of refinement, this is done in the same manner. Breathe it back in.
Shen is more potent than jing, and chi more potent than shen, so refining your energy through breathwork will give you more [usable] energy in day to day life. It's not really "more energy" in a technical sense, but more available energy. Compare crude oil to petrol at the pump to rocket fuel. That's jing/shen/chi.
Exercise to refine energy: Breathe while pulling the energy up your spine, pool it in the dan tians and continue this practice until you feel content, anywhere from one minute to an hour or more is appropriate. I suggest 5-10 minutes for a start, just to get used to paying attention to your posture. There is no one posture that is acceptable, you just want a stable, comfortable posture as close to at all times as possible. Returning your mind to your posture, breath and internal energy network as often as possible = working your internal energy as often as possible = absorbing and refining the most energy possible = having the most energy possible and exiting this life with more energy than you came into it. I don't set aside time to do this exercise, I squeeze it into every waking second of my life.
In the beginning, you may only feel the energy pool in the lowest dan tian, but with a bit of work on refinement you'll feel the energy in the other centers too. Note that the middle dan tian is not located in the heart, it's more like just behind the lower end of the breastbone. Just like how the lower dan tian is below the diaphragm (when you breathe in, you pull the diaphragm and lungs from the lower dan tian), not in the stomach (but the energy there can feel like a "fullness" similar to a full stomach, you'll know you're feeling the energy center if you can feel this when you're fasting and know it's not just food lol).
A common byproduct of energy refinement in this system is an elevated body temperature, so don't be surprised if you break out into a sweat at some point, that just means it's working. With some more attention to your breath, you can keep your body temperature from raising while you do it, but in the early stages of your practice I would take it as a win.
GLHF