I have studied this stuff for 40 years. I have boiled it all down to two things. Concentration and relaxation. The more you relax, the more you are able to concentrate. The more you concentrate, the more you are able to relax.
LIE DOWN to meditate. If you feel sleepy, so be it, sleep. Eventually your body will have had enough sleep, which will enable you to concentrate without falling asleep.
Concentrate on ONE THING ONLY. Preferable the physical sensation of your belly rising and falling as you breath. Ignore every thought that you have. Ignore every other sensation you have.  The sensation of your belly rising and falling is the last physical experience you will have while developing deep relaxation. This is why it is the best area to concentrate on.
At some point, if you relax enough, it will seem like your breathing has stopped. It has. This is where the "fear" aspect of insight comes from. However, there is nothing to fear. Your body is in such a relaxed state that it does not need much oxigen to survive. This is the moment that has been written about and made famous thoughout history with stories like the "leap of faith", or "slaying the dragon", ect.
Once you push yourself enough to keep going pass this feeling of imminent death, which it REALLY does feel like because we all feel the need to breath to live, the first time, then you will experience something that will change your entire outlook on life, completely. 
Going through the experince will have the most profound effect on your life, more than anything else you have ever experienced.

How about adding mindfullnesss.  

Humans have studied this stuff for thousands of years and have arrived at a multitude of ways to approach spirituality. There is more than one way to the top of the mountain. It's a happy thing that you have found your way but let's not pretend it's the only way.

Every single path up the mountain involves extreame concentration. That is the whole point. Whichever path you take. It may appear different at the beggining, but eventually it involves extreame concentration. 

Can you please supply the details? I think everyone would benefit from your wisdom and knowledge across the broad spectrum of traditions:

Zen?

Sufi?

Souix?

Christian?

How is concentration developed and used in these traditions?

The word "extreme" is interesting to me... what qualifies as extreme concentration?

Thor has a hammer you know (pun intended). And often, to someone with a hammer, everything resembles a nail 

Mindfullness is thinking. It is to be avoided.

Sounds extreme.