Music, language learning and fitness all fall into this category of things that are difficult because they require so much regular investment, are optional in every day life, but anyone could in theory do them. For things like this, the number one factor any teacher or system should be optimizing for is motivation. No matter how important every other goal is, if you don't optimize for motivation people will just never learn. If you can't make it fun, don't even bother trying to teach most people, because only those with a burning passion will make it across that hump where it begins to have a real impact.
For examples of this effect in language learning, check out the writings of All Japanese All The Time, and for this in fitness, see Crossfit where the group setting and competitive features provide additional motivation and is wildly successful.
Of course, this doesn't ONLY apply to those things. This is also the secret of success for unschooling. As far as I have heard unschooled kids have the effortless joy of learning whatever they want at their own pace end up going much deeper on subjects that are of interest to them, and in the end they end up only 1 grade level behind their peers who went through 12 years of relative suffering.
For examples of this effect in language learning, check out the writings of All Japanese All The Time, and for this in fitness, see Crossfit where the group setting and competitive features provide additional motivation and is wildly successful.
Of course, this doesn't ONLY apply to those things. This is also the secret of success for unschooling. As far as I have heard unschooled kids have the effortless joy of learning whatever they want at their own pace end up going much deeper on subjects that are of interest to them, and in the end they end up only 1 grade level behind their peers who went through 12 years of relative suffering.