Once you accept this as your daily practice then you have to practice with a lot of confidence

If you are practicing something from other traditions, if you are practicing ngondro Longchen Nyingthik, you have to have a lot of confidence in your practice in your lineage. Do not hesitate. Once you accept this as your daily practice then you have to practice with a lot of confidence. Because I see some people are not sure about the practice [they are doing]. They are not sure what they are doing, but they practice this and do other things some other time. Uncertainty is a big cause for not doing improvement and you waste your time and energy. So certainty is very important for having strong belief in [the practice]. So you will make improvement, you will get good benefit from that.

If you look at Guru Rinpoche, for example, [you see] Guru Rinpoche accomplished enlightenment in his life and all of other masters like Garab Dorje or Longchenpa [did too]. Countless masters accomplished enlightenment in one single life through the practice of Dzogpa Chenpo, of Longchen Nyingthik. That means Longchen Nyingthik is very reliable, very genuine, therefore there is nothing wrong if you trust it and practice diligently. Do not hesitate, do not have any second thought, but put all your efforts and you will get great benefit from that. Those great masters said that if one do not do great accumulations one would not have chance to meet such profound teaching. Therefore, I think we have done very good accumulation so we meet this profound and authentic teaching and practice. So one should be happy to have a chance to have such a great Dharma and practice.

Hungkar Dorje Rinpoche, “There is Still Harmony – the Community Still Continues”