As far as I see it - the problem is not in too much effort, not in sati, not in wanting or not wanting enlightenment.
The answer is "the time has not yet come". You can't win enlightenment by spending hours in meditation. It doesn't work that way.
You have to accumulate enough numerous positive qualities, cleanse the mind of negative ones and have enough kamma fruits for this.
Ajahn Chah said that it doesn't matter when you will attain nibbana, because you can't force the result to come as soon as possible.
What you can do - is to cultivate Noble Path according to your present skills, kamma, virtues. And that's it. No "secret practices".
This sutta, though short, is very imporant for many meditators to understand:"These are the three urgent duties of a farming householder. Now, that farming householder does not have the power or might [to say:] 'May my crops spring up today, may the grains appear tomorrow, and may they ripen the next day.' But when the time has come, the farming householder's crops spring up, the grains appear, and they ripen.
"In the same way, there are these three urgent duties of a monk. Which three? The undertaking of heightened virtue, the undertaking of heightened mind, the undertaking of heightened discernment. These are the three urgent duties of a monk. Now, that monk does not have the power or might [to say:] 'May my mind be released from fermentations through lack of clinging/sustenance today or tomorrow or the next day.' But when the time has come, his mind is released from fermentations through lack of clinging/sustenance.
Also fits this topic -)http://www.youtube.com/watch?v=T_Og8K81M6E