The Sufis explain this very well.
The key to success in worship lies in meditative reflection (fikrat)…whoever persists in such reflection in the heart will behold the invisible realm in the spirit.
Whoever contemplates God through keeping watch over the thoughts which pass through his heart will be exalted by God in all of his outward deeds.
–Dhū’l-Nūn Miṣrī in ‘Aṭṭār: Tadhkirat, 154-155
Meditative reflection is Serene Reflection mentioned by Samael Aun Weor, otherwise known as Mo Chao. In order to develop serenity, we must learn to concentrate. Therefore, build yourself up through concentration practices, mantra, prayer, etc., so as to assist with reflection (imagination) in retrospective meditation without forgetting what your doing or being cloudy in the mind.
Serenity is developed, meditative reflection (fikrat) (or serene mind and imagination) is cultivated through the remembrance of the Being, whether we are performing mantras, breathing exercises, pranayama, sexual alchemy, etc. Focus on God within, who is also within your breath!.
[Al-Jurayri] said that whoever does not establish awe of duty (through respecting the practices of this tradition and being consistent with one's practices) and vigilance in his relationship to God will not arrive at disclosure of the unseen or contemplation (mushahadah, to bear witness) of the divine. —Al-Qushayri, Al-Risalah