"5. Deliberate practice isn’t much fun."

This isn't necessarily the case. It's true that practicing to improve in something you're not really enthusiastic about can be a burdensome chore, but the case is far different when it involves something you really enjoy. 
In college/grad school, we are required to be proficient in many areas, some of which may be far from our favorite things. This is where the required practice can be much more challenging since the motivation is only external...such as the desire to get a good grade.

Ted Williams, Mozart, Tiger Woods, and other stellar talents spend countless hours practicing out of love for what they do. Their motivation is internal. When you truly enjoy an activity, it's easy to be driven to do what it takes to improve. All that effort will also be enjoyable because they know the end result is being even better and enjoying what they do even more. 

As the saying goes, if you do what you love, you'll never work another day in your life.

As a personal example, I spend long hours on weekends using historical data to practice day trading. To someone who isn't interested, this would be extremely boring and tedious. To me, it's challenging and fun. =)