In my opinion, it differs between players. I cite the below as percentages of brainpower used for each task in a round:

Top 20 in the world: 60% course management 40% mental strength

21 - 80: 50% course management 45% mental strength 5% worry

81 - 250: 50%, 40%, 10%

outside top pro tours (but professional) : 40%, 20%, 40%

Good amateur (up to 4 handicap) 30%, 30%, 40%

5 - 9 handicap: 30%, 25%, 45%

10 - 14 handicap: 20%, 20%, 60%

above 14 handicap: 10%, 20%, 70%


Didn't get these from anywhere, just made them up to see how people react (but they are how I view the mental approach across the golfing spectrum). In most endeavours, the ability to succeed vastlt depends on mental aptitude, not necessarily physical gifts.