You can develop, cultivate, and protect your mind as you go for great benefits to come, says Buddha. You risk danger, suffering, and possibly harm if you don't. And if you go about in unproductive ways, or dangerous and harmful ways, you could be in for sufferings too. Therefore, for development work the help of a guru in the Self is indispensable after the guru takes charge out of compassion [Geta 32, 44]. Gracious gurus are not dispensed with in some of the major traditions of Buddhism either.
Now, what is given below in the form of capsules are extracts of presumably basic Buddhist teachings. My modifications are shown by the mark #. - TK
When developed and cultivated, the mind leads to great benefit and happiness; when undeveloped and uncultivated, it brings about stress, suffering, great harm. [Anguttara Nikaya 1.27-30]