In parallel, and building on the first and second signs that one is progressing to support harmonized Soul creation, is the 'third sign' - which is when one has consciously developed the ability of intentional suffering.
Unfortunately, 'suffering' has been so misunderstood in modern culture that it is treated with fear, avoidance or derision. However, it is one's capacity for suffering - that patient endurance of a fundamental 'friction' evoked through the struggle between desires and non-desires - that can open the door to higher realities that are not perverted by associative imagination or fantasy.
Broadly, there are two forms of suffering - 'unconscious' and 'conscious'.
Unconscious suffering is the suffering that everyone experiences and is most dominant. We do not know why we suffer, only that we suffer. Anxieties, stresses, mental illnesses, all flowing into a variety of psychosomatic diseases are common forms.
Unconscious suffering's chief feature is that it is mostly or entirely unproductive for the individual. It serves only to harm, reduce health and wellbeing, and deplete those energies most needed for spiritual development.
The 'antidote' to unconscious suffering is 'self-calming' - a habit to quickly 'anesthetize' the friction we feel through many forms of self-justification and denial, and even chemical means through drugs and alcohol. Unfortunately, self-calming only serves to drive the suffering further into unconsciousness.
There are two forms of conscious suffering - 'voluntary' and 'intentional'.
Voluntary suffering is that suffering we are willing to undergo to achieve a personal aim or objective. For example, completing a project, obtaining a university degree or even achieving spiritual goals.
Most people have experienced voluntary suffering to one degree or another. It is not to be confused with the suffering that we are 'compelled' to go through by life itself as that belongs to the realm of unconscious suffering.
Voluntary suffering is deliberate, going in with 'eyes wide open' and accepting all the uncomfortableness and stresses and strains for the sake of the reward at the end. Its chief feature is that the 'results' of the voluntary suffering always flow into strengthening the 'Ego' (the 'evil one' or 'evil' in Biblical terminology).
The action of voluntary suffering is legitimate to a certain extent in order to stretch oneself in life and develop one's functional capacities to the fullest. However, inevitability, it only crystallizes something that can close the door to full Soul creation unless consciously ameliorated.
A definition of 'Egoism' is the "…constant denial of all other existences except one’s own and/or the constant affirmation of one’s own existence at the expense of all others…"
A fully 'overgrown' Ego - that is exceptionally common in modern culture - effectively 'swallows-up' or 'cuts-itself-off' from any connection to higher qualities. This is the most tragic fate for anyone.
Intentional suffering is that suffering that may come as a result of impartially helping others. This is subtle as often voluntary suffering is confused for intentional suffering.
True help for the welfare of another is almost always at the expense of one's own. Genuine help is never convenient or done in one's 'spare time'.
Real help requires intentional suffering because it is only through intentional suffering that higher qualities of energy are able to enter the situation to provide what is needed - and in so doing, transform it.
For example, almost always when two people are having a conversation, it is not really a conversation - both a just 'waiting to speak'.
Really listening to someone requires an effort to restrain from speaking (inwardly and outwardly) and simultaneously 'receive' what the other person is saying - then a true exchange can appear. This is extraordinarily difficult, and occurs rarely.
However, the motivation, the 'intention', behind this act is not a reward for oneself - not to manipulate the situation for one's gain or derive strength or power - but simply to support the 'impartial needs' of the other person.
It may be that the other person can't stop talking and 'rambles on' - but one accepts this, no matter how disagreeable or uncomfortable, and suffers for them. Alternatively, it may be necessary to stop the person from rambling to help them, and yet, this may produce a negative relationship for while, the consequences of which we accept to bear.
Parenthood is another example. If parents 'take themselves out of the equation' and diligently attend to the needs of the child for the child's sake and not theirs, intentional suffering often comes. If parents take care of their children only to 'mold them to some ideal of theirs' rather than what the child actually needs, voluntary suffering predominates with often tragic consequences.
Worship is yet another example. Whether to a spiritual personage or God or to a merited ideal, to place one's trust in wisdom of a higher order rather than one's own limited, egoistic nature, is to move in the direction of intentional suffering.
The lives of the great spiritual figures of history are strewn with intentional suffering, ultimately sacrificing themselves in some form for the benefit of others. The drama of Jesus Christ is a notable example.
Suffering is, in the beginning, uncomfortable or even painful because we do not know how to suffer. When we begin to develop intentional suffering, which takes years of dedicated practice, suffering itself can be transformed into a subtle joy.
Not that one seeks out suffering as this can very quickly turn into voluntary suffering and fuel the Ego. But when suffering comes in the service of others we don't avoid it. We can begin to see joy and suffering like two legs - both are needed to walk, even run, otherwise, we just go around in circles.