We are pyhiscal beings as much as we are spiritual. Sometimes, because we are on the go, we are totally unaware of the signs our bodies are giving us to slow down or pick up. How we treat ourselves, what goes in our digestive system and our minds, how are muscles are used and how often, from our skin and muscles to our minds and memories affect us.
I have been training for a decade plus, using a variety of modalities such as HIIT, Boxing, Bodybuilding, Crossfit, and I have learned what works and what doesn't work. I've learned that fitness, represents our physical bodies, but includes both science and intuition.
Your gut is your second brain. When you feel your gut instinct telling you something, that's your second brain trying to speak to your first brain. When your gut is out of wack, your intuition is too. It's usually a sign of imbalance. When there is stress on the body, the consequences can and usually will, show up as a physical symptom.
Exercise, recovery and nutrition compose your fitness levels so how you eat, manage stress and how you train or move all play a role. Do not underestimate this.
Sleep isn't for suckers, being skinny doesn't make you fit. Operating at optimum capacity is fit. Your body is a vessel.