Thread is a bit old by now - I've also been in the area of meditation and Eastern spiritual teachings and techniques for a long time. Wholehearted agreement on the various comments that this is powerful stuff, you're learning to consciously intervene in very intimate aspects of your functioning that are normally left to happen more or less on their own (e.g thinking, breathing, and engaging or disengaging your attention). So there is definitely potential for doing it wrong and making a mess of yourself.

One thing I think has not been mentioned here, is that contemporary culture is very mind-centered. We identify much more strongly with our thoughts than with our feelings, and when feelings are emphasized, it's usually negative ones (see the current culture of outrage). We feel that we are what we think, and tend to work through things by thinking them through. Heart to heart connection is still a thing, always will be because it's part of being human, but it's not very much emphasized in our cultural environment.

So you end up with people taking up forceful, advanced spiritual techniques, and doing it it all from the mind, out of plain conviction and volition. And unless you happen to find very good guidance, that's not altogether unlikely to screw you up.

Every spiritual tradition that I've looked at has a strong component of heart connection at its center, but it's not always very explicit. Theravada Buddhism has metta as an practice, but it's done separately at certain times, rather than emphasizing that it's the prerequisite for the shamatha/vipassana stuff to actually help you rather than mess you up. A strong, secure heart connection is what makes your meditation go in the direction of wholeness rather than dissociation. All sorts of spiritual traditions are connected to religions that teach you to love your God or your Guru or your favorite enlightened being, or all sentient beings, and they usually have some form of formal worship too, e.g puja. It's not the object of worship that makes the difference, or the details of the ceremony - it's what the reverential, loving attitude does to you. Without love as the lubricant, spiritual practice is not only often ineffective, it's downright dangerous.

"When a person who wants Truth more than life falls in love with what is, it happens." - Bart Marshall, on spiritual enlightenement. Note the "love" part is just as important as the "truth" part.

One problem nowadays with all the cultural crossing and mixing, is that we get taught Eastern practices, and either the reverential aspect is lost in the process of Westernization, or even more insidiously, it gets transmitted but doesn't work for us. You're a grown up adult joining a spiritual community, and you might learn that it's customary to bow down to a statue, or make an elaborate puja once or twice a month, you go through the motions, even enjoy it, enjoy the connection with fellow practitioners, but the deep heart connection is not really there, because you're a jaded adult who didn't grow up with this particular figure you're now bowing to or making offerings to, and anyway why would someone offer food to a stone statue? Get caught in the social aspects of it, and you might not even notice that an important part of your chosen spirituality is just not working.

One thing to take away from my rant: if you're doing any kind of spiritual practice, please please make sure you open your heart before, during and after, in whatever way actually works for you.