A muscle grows stronger only when stressed beyond its initial capacity. After stress, a recovery period heals and then builds-up the muscle so that it is stronger than the pre-stress capacity.
With too much stress on a muscle without chance for recovery and subsequent build-up, the muscle will only weaken into a conditioned termed over-training.
With too little stress or with too long a recovery period, the muscle will fail to increase capacity due to lack of sufficient stress. Also, gains from the initial stress do not last for long and once sufficient recovery has taken place, a greater stress must be applied within the appropriate time frame to build upon the increased strength.
Perhaps this can also be applied to your mental growth. It may be that without struggle, you will not grow. It may be that struggle must play as vital a role to your life as air and food. Embrace your struggle and learn from it because it will be your only true mentor.
Seek out struggle in order to learn but do it judiciously as too much stress without sufficient recovery will only set you back. Build upon successes with more and greater struggles. Do not sit aside once a single victory has been won for gains are short-lasting and must be maintained.
If you were taught that struggle is something to avoid then were lied to. If you were taught that your life should turn out to be non-stop joy then you were lied to. If you were taught that life is anything but struggle then you were lied to. You will and you must struggle for survival as your ancestors did before you. "Survival of the fittest" is not just a catchy slogan, it makes the point that everything alive today is here because it overcame struggle.
Modern society has removed so much struggle from us that we are flaccid weaklings not fit to survive. You knew back in the day, when we hunted and gathered our food, that every last member of the tribe was a vital and valued member. Daily life was a struggle and if you did not meet that struggle you surely died. If others cared enough about you then you survived for another day. You struggled at food procurement and you struggled to build social ties. Once you sit back and no longer struggle then you are left out to die. There are no laurels to rest upon.
Modern society's removal of so much struggle has also fooled you into thinking that struggle is an unacceptable way to live and that something must be wrong if a challenge presents itself. You are shocked when you find yourself in the middle of a struggle. And if you have no previous experience in overcoming struggle, you are lost. There is no such thing as tragedy; it is called life. A tragic situation is just another day in the game of life. Struggle goes hand-in-hand with living.
Do not shrink away when challenge presents itself; overcome and grow from it. Build up your ability to handle struggle by engaging in it so that when greater challenge comes you are ready for it.