I recognize that this may seem a bit off topic, but bear with me. It’s been my experience that most creative people (writers, musicians, visual artist, etc.) rarely have a problem with the creative side of output. That is to say, we generally can come up with at least half-formed ideas without difficulty, but the hangup usually happens because of a lack of discipline. Writers don’t write enough to get an intuitive grasp on their application of prose, musicians don’t want to put in the mind-numbing hours required to perfect their technique or get their performance as a group as tight as it needs to be. We procrastinate and make up excuses like writers block or creative exhaustion.
Work of any kind is hard if you push yourself to to the limit of your current abilities (which is how one improves). Creative work is no different in this respect. Why should it be? Personal discipline will often be the limiting factor in how good a person gets. When I was teaching guitar in high school I had students who had an unbelievable degree of raw musical talent. One kid was able to play along with songs on the radio and improvise guitar solos with a full band after literally four hours of learning time. He never did anything with it beyond occasionally jamming with friends. I had other students of mediocre natural ability who would practice scales and fingering drills three hours a day with a metronome in addition to their regular hour of practice. Guess which kind of student has their music on movie soundtracks right now.
The discipline necessary to build and maintain fitness -which I’m defining as muscular strength, power and endurance, as well as cardiovascular endurance- is the same discipline that keeps me on track when I’m writing or playing a song again and again until I’m happy with it. It’s not forced work, it’s work as a fulfillment of an internal drive. I start craving weight training if I’ve neglected to make time for it after a few days in the same way I crave writing when my head is bursting with ideas and I need to get them down. Discipline is discipline and we’re all a bit too old for the “nerd vs jock” paradigm. A hard workout gets all the monkeys off my back and unlocks both creative drive and single-minded focus. Do some some chin-ups and run sprints in the park. Learn the right way to squat and deadlift. A strong mind and a strong body aren’t incompatible.