To understand effort and effortlessness, an analogy to skills like swimming or cycling is helpful. Initially, we have to invest quite a bit of effort to learn these skills. Eventually, when we have learnt swimming or cycling, we are indeed investing effort when performing these activities. However, our performances are also 'effortless' because these skills becomes second nature to us :)
A duck is another good example. At the surface level, the duck seems to be gliding effortlessly on water. A quick peek at the duck's feet shows great effort being invested. However, gliding on water is second nature to a duck. Is effort being invested? Yes. Is it effortless? Yes.
Many people come in touch with the main practice (acceptance, non-attachment or equanimity) by hearing it from somebody or reading about it. Some people then analyze what they read. Some people discuss their understanding with friends and family. A few start writing articles and giving lectures. All of these steps constitute 'initial exposure to knowledge' and 'intellectual understanding'.
However, going beyond initial exposure and intellectual understanding is important. We have to assiduously practice acceptance, non-attachment and equanimity in our daily life, moment by moment. Only through continual practice do we acquire the skills to be in a positive state of mind throughout the day.
Buddhism: Our journey towards knowledge acquisition is broken into three stages: Sutamayā paññā (knowledge derived from hearing), Cintāmayā paññā (knowledge derived from intellectual analysis) and Bhāvanā mayā paññā (knowledge derived from direct experience). For details, see Panna in Buddhism. For knowledge via direct experience, what is required? Practice, practice, practice.
Attendees of the 10-day Vipassana retreats may recall S N Goenka's frequent reminders during the course: 'Continuity of Practice is the Key to Success!'
Advaita Vedanta: In this tradition, progress is broken into three stages: 'Shravanam' (hearing spiritual wisdom), 'Mananam' (evaluation, analysis), 'Nidhidhyasanam' (meditation, absorption, practice). The last step is key: practice, practice, practice.
Sikhism: In this tradition, progress is broken into five stages: Dharam Khanda (initial exposure to spiritual knowledge), Gyan Khanda (deep knowledge of scriptures; intellectual knowledge), Shram Khanda (assiduous practice of what has been learnt), Karam Khanda (grace, effortlessness), Sach Khanda (experience of Oneness). After an initial exposure and after amassing intellectual knowledge, what is the next step? Practice, practice, practice.
A common saying among the Sikhs is "Sukh Vele Shukrana, Dukh Vele Ardaas, Har Wele Simran", which means "Thankfulness during times we feel blessed, prayer when we feel miserable, and remembrance (of God) at all times". The word 'simran' is equivalent to 'constant practice'.
Yet to write: In each of the systems, the sequence of steps is not linear. Let's say the sequence is A → B → C. Then progress in B is enabled (made possible / made easier) by progress in A. Similarly, progress in C is enabled (made possible / made easier) by progress in B. However, A, B and C help each other.
An inspiring couplet ('doha') by Kabir (1398-1518) that emphasizes constant practice:
A one-line summary of the above couplet is the German saying Übung Macht den Meister ("Practice makes a master" or "Practice leads to perfection").
Kabir's couplet reminds me of S N Goenka's repeated urges 'Continuity of Practice is the Secret to Success' and his assurances: 'You are bound to succeed'!