There are two different paths tzaddikim can take, both of them derive from divine da'ath. Da'ath, knowledge, splits into hesed (giving) and gevurah. (holding back)
The path of hesed which is open to the tzaddik involves jumping into the thick of existence and destroying your ego through recognizing and experiencing great Ahavat Yisrael. Knowing that you yourself are nothing and that everyone around you is priceless. This may sound hard and depressing but it isn't simply because everything and everyone around you is so sweet and precious, it causes infectious happiness.
The path of gevurah, which is meant for other tzaddikim is an even higher path but it is found in tremendous worldly suffering. Through subjecting oneself to deep physical hardship and attaching oneself solely to the spiritual one's spiritual joy and accomplishments are practically unbounded. This path, the Komarna explains is frought with a number of dangers, most notably depression.
The Komarna Rebbe describes a few Tzaddikim who represented the first category, foremost among them, the Baal Shem Tov.
There is a story about the two brothers, Reb Zusha and Reb Elimelech:
R' Zusia and his brother R' Elimelech had an ongoing dispute on what should one base his service of God. R' Zusha maintained that one should first reflect upon his own lowliness which would in turn cause him to appreciate God's eminence. R' Elimelech held that by contemplating God's eminence, he would come to realize his own insignificance. Since neither brother could sway the other, they went to the Maggid of Mezeritch for a judgment as to whom was correct. "You are both correct, explained the Maggid, both paths are valuable. But the one who begins with himself is safer . . . one can't fall from the ground".[from: http://www.judaicaplus.com/Tzadikim/tz_viewer.cfm?page=zusha.htm]This story sort of highlights the two paths. Reb Zusha was a (to my mind) proponent of the path of hesed, and Reb Elimelech of gevurah. I think the story points out the relative safety of Reb Zusha's path, the path of hesed, over the path of gevurah. In terms of impact and accomplishment though, Reb Zusha insisted that Reb Elimelech (the younger brother) was the greater of the two.