Other words we could use in place of sagacious are: wise, sage, discerning, clever, intelligent, judicious, acute, sharp, keen, perspicacious.
Wisdom is not learned easily.
As Confucius said:
By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest.
It takes time and experience to become wise; it also takes a recognition of the facts, seeing things as they are, rather than how you would like them to be.
Enjoy the journey!