If we keep our muscular activity below the threshold above which muscle tissue is torn, we never give our muscles a chance to heal and gain strength. Certainly, we can keep our tone up and stay in shape, but if we ever let our habitual steady level sink too close to the atrophy level, we will, over time, need more and more effort to maintain the same physique. Only if our muscle tissue endures true tearing pain and actual cellular damage, can we become stronger, larger, more robust, and healthier.
Likewise, only if our hearts experience true shocks from time to time, and only if our "psychic tissue" is torn down on a regular basis, can we hope to achieve emotional and social maturity. This is hardly a prescription for masochism or wild risk-taking. It just means a commitment to progressive involvement in reality. Feeling the pain of torn muscle tissue, our nervous system naturally urges us to cease the motion and retreat to a comfortable stance. But our commitment to health and greater vitality spur us on to "play through the pain" for greater gains. In a similar way, when we feel the trauma of emotional conflict, we are inclined to retreat from the source of our irritation into a safe "holding pattern." If, however, we are fundamentally committed to facing reality, and facing those who share reality with us, we will endure the pain of emotional surprises and shocks, knowing that such woes actually yield our growth.
Struggle is a sign of life. We may worry about rescuing a flailing man from deep water in time, but we needn't rush to pluck out the man just floating there, face down, silent, motionless, as if he were calm and at peace. If our relationships with family, friends, lovers and coworkers were steadily free from surprises, resistance, and friction, we would begin to atrophy on multiple levels. We would become like the "humans" in WALL·E: swollen with comfort, limp with leisure, bloated with bliss, and fatally detached from and numb to reality buzzing around us. Struggle is a sign of life.
If you were to lie still for 24 hours, you would die. Your lymph system is designed to be in motion and keep the impurities flowing out. From one perspective, astronauts have it easy: they can lift heavy objects like feathers and glide wherever they want with the push of a finger or toe on any object. But their ease is also their peril: removed from the steady grinding pressure of gravity and the cumbersome pounding of our legs in motion, astronauts' bones begin to deteriorate. So, to prevent this, they must stand on a vibrating pad a few times a day, just to shock and jar and irritate their bones into staying healthy. So it is with the heart: only if we bear the steady grinding pull of others on us and maintain the cumbersome progress of climbing up and down and over and behind and around the obstacles generated by others, can we jar our minds into mature relational health. Struggle is a sign of life.
The trick is to keep moving. But this trick, like all tricks worth watching and learning and performing, is a trick made possible by grace. In the words of the prophet Isaiah (chap. 40):
 Have you not known? Have you not heard?
The LORD is the everlasting God,
the Creator of the ends of the earth.
He does not faint or grow weary,
his understanding is unsearchable.
 He gives power to the faint,
and to him who has no might he increases strength.
 Even youths shall faint and be weary,
and young men shall fall exhausted;
 but they who wait for the LORD shall renew their strength,
they shall mount up with wings like eagles,
they shall run and not be weary,
they shall walk and not faint.
At times grace helps us fly, but at other time it may just be the fumes we need to keep walking, to keep on moving, to keep going, to keep the left foot switching with the right, no matter how slowly, and now matter how many blisters shriek for us to stop moving on. We are not called to suffering as such, but we are called through suffering to glory and health and wisdom on the other side. Being created in the image of the Triune God, we are inherently relational beings. There are no pure individuals, and, therefore, there is no purely individual growth or wisdom. Everyone has a mother and a mother tongue, neither of which he invented or chose. We are in this together or we are not at all. The fecund collectivity of human nature does, alas, bring with it a price, namely, the price of me putting up with all you other folks (or vice versa, depending where you're looking from). We might be happier, in some abstract realm, "all on our own," but we would also lack the goods which collaborate to produce human maturity if we were not crammed into the restless grinding mesh of human existence. We might be happier apart from others, but we would not be ourselves apart from them. This paradox holds preeminently in the Church, the Body of Christ, since, in fact, it is the social and familial orders which take their shape, providentially, from the Triune-Christocentric sacrament known as the Church. As we read in Philippians (chap 1):
 Only let your manner of life be worthy of the gospel of Christ, so that whether I come and see you or am absent, I may hear of you that you stand firm in one spirit, with one mind striving side by side for the faith of the gospel,
 and not frightened in anything by your opponents. This is a clear omen to them of their destruction, but of your salvation, and that from God.
 For it has been granted to you that for the sake of Christ you should not only believe in him but also suffer for his sake,
 engaged in the same conflict which you saw and now hear to be mine.
We are, again, called not to co-suffer with Christ, just for divine kicks. Rather, co-suffering with Christ is a function of His hypostatic, consubstantial union with us as co-existers. Christ only suffers in the Church because He has deigned to incorporate us into His Eucharistic covenant. We, in turn, only partake of His suffering in the Church because He animates the Body, only because His Body is alive, in motion, restlessly pursuing the divine glory. Because the Body is alive, and we are in the Body, we will, naturally, feel the supernatural trauma of a living body just like muscular cells feel the trauma of exercise.
Don't say "I believe" if you're not prepared to be torn. Don't say "I love you" if you're not prepared to cry. Don't say "We're in this together" if you're not prepared to regret the unity and yet still keep trudging through. Don't say "I want to live" if you're not prepared to shear away and tear down whatever would drag you down to death. Love someone who will always "shock" you out yourself into your better self. And then love that someone in the One who shocked Himself in order to tear us out of the dying body of the world into His living, moving Body called the Church!