Well, the problem is rather simple. If you decide to only engage in mindfulness, you'll have a great time discovering things about yourself and your environment

Well, the problem is rather simple. If you decide to only engage in mindfulness, you'll have a great time discovering things about yourself and your environment. You will feel better about yourself. That will work for a while and it might set you on a larger, longer path with more peril. In (Mahayana) Buddhism you train more. Like the opposite: concentration. Think about the same topic for one hour, repeatedly. Who am I? Who do I think I am? What thoughts am I suppressing? Fundamentally, it teaches you that all these things are like sliders on a big mixing console. Pushing one slider will bring the others down. Pushing mindfulness might reduce equanimity and concentration. In the end, it is the art of letting go. If you want to hold on to something, you should be able to let it go.