Do you believe that “the mind works the way the mind think that it works”? (I do.)
The most specific example of this that comes to mind for me is- if you believe that exercising willpower drains your willpower, then that is true. And if you believe that exercising willpower strengthens your willpower, then it does! http://news.stanford.edu/news/2007/february7/dweck-020707.html http://mindsetscholarsnetwork.org/wp-content/uploads/2015/09/What-We-Know-About-Growth-Mindset.pdf
No, I don’t, or only a little bit. See Moravec’s Paradox: the easiest tasks to program a computer to do are those we are most conscious of. There are parts of the brain that are remarkably plastic, but there is a lot of background processing that we are not aware of.
If you don’t believe that exercising willpower drains your willpower, then it actually still does, but you just don’t notice it as soon. This has been tested. It’s also true that certain mental abilities can be improved with practice, this is just plasticity. Think of it like exercising a muscle. If you overexert yourself, a strong instinct will try to stop you from hurting yourself. Trained athletes can overcome this instinct to some extent, but they still have real physical limits. And of course, appropriate exercise can improve performance over the long term, but again there are real physical limits to how much.