I'm surprised you 'don't see how inner motivation exists'. Personally i can see plenty
- The pleasure to find out / understand new things (ex : how to brush the ball etc..)
- The physical feeling of good shot is very nice
- The physical effort and moving a lot, being tired (sport and dopamine)
- The pleasure to be 100% focus and play fully
- Etc..
I'm also driven by external motivation (winning, respect etc..) but i don't feel that's the main factor. And still i train hard as i like it (so no lack of motivation)
You're right, inner motivation does exist, but it's a bit more complicated than what you wrote, I think.
If to really go into it, there are 6 motivators for human kind:
1) food (the basic desire to survive and feel 'alive', also an animal motivation)
2) sex (the desire to procreate, also an animal motivation)
3) money (the desire to guarantee future survival and comfort, already a human motivation)
4) respect/glory (a wholly human motivation)
5) authority/control (exerting one's will over others)
6) knowledge (the 'inner' motivation)
By this scale people go from animal-like to human. But it's really nearly impossible to differentiate them, even a person himself doesn't know what motivates him exactly and it is a combination.
A person can say that looking good is an inner motivation that he gets pleasure from, but in truth his motivation for it may be respect or sex etc.
The pleasure of feeling a good shot, yes, but is it more pleasure if someone else is watching? maybe it's only pleasure if someone else is watching?
And if nobody is watching, do you enjoy the good shot only because of the good shot, or are you being motivated by the fact that you learned a good shot that you could later use in a game where people will be watching, where you'll win a competition, etc?
Without very close inner scrutiny you can't really tell what the real motivation is at root, if inner or external. That's why I say I don't see evidence for the existence of inner motivation, though theoretically yes I agree there is such a thing in general.
I think what makes us truly human, as in, distinct from animals, is the desire for status among peers, and so that is probably the main motivator. It is obviously the easiest way to motivate people to do something, in any case. Peer pressure it is called, where the most powerful instrument is envy. I would say number 6 doesn't play much of a part in the very intense and so called 'abusive' education of children, I would say.