For the overconfident

Cicero, On Duties, Book I, p. 36

...Men whom success has made unbridled and overconfident should be led into the training-ring of reason and learning, so that they perceive the frailty of human affairs and the variability of fortune.

The virtue that fights on behalf of fairness

Cicero, On Duties, Book I, p.26

The Stoics define courage will when they call it the virtue which fights on behalf of fairness...a spirit which is ready to face danger, but is driven by selfish desire rather than common benefit should be called not courage, but audacity...it is a hateful fact that loftiness and greatness of spirit all too easily give birth to willfulness and excessive desire for pre-eminence...the loftier a man's spirit, the more easily he is driven by desire for glory to injustice. This is slippery ground indeed: scarcely a man can be found who, when he has undertaken toil and confronted dangers, does not yearn for glory as a kind of payment for his achievements.

On the danger of distraction (especially those distractions in which we are successful)

So what can we expect if we take on this additional project, especially since it wont just distract us from weightier matters, but will be no small cause of pride and egotism?

From the chapter entitled - "That talents are treacherous for the uneducated"
(Discourses, Book I, Chapter 8)