we do these things because they are hard

וַיַּ֤רְא מְנֻחָה֙ כִּ֣י ט֔וֹב וְאֶת־הָאָ֖רֶץ כִּ֣י נָעֵ֑מָה וַיֵּ֤ט שִׁכְמוֹ֙ לִסְבֹּ֔ל וַיְהִ֖י לְמַס־עֹבֵֽד׃ 

The pasuk seems to be a stira minei u'bei: Yisachar saw that a life of menucha is the way to go, but then the pasuk tells us that he bent his shoulder under the burden of work that he accepted upon himself.  What happened to the life of rest that was so good?

The meforshei pshat explain (with slight variations on this same theme) that "menucha" here means, as opposed to Zevulon who went out to sea, Yisachar saw that it was better to work the portion of land at home that was allocated to him.

R' Tzadok haKohen tells us that if you want to know what your mission in life is, look at what the yetzer ha'ra tries to tempt you with.  It's by overcoming what you find to be a challenge, what you find difficult in avodas Hashem, that you grow and develop, and that's your task in this world.  

My wife likes to quote JFK's statement, "We choose to go to the moon... and do the other things not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills..."   The yetzer ha'ra makes certain things hard for us, but by doing those very things we develop our energies and skills to the fullest.

R' Ashlag, the Baal haSulam, explains that precisely because Yisachar saw "menucha ki tov," that taking it easy was what appealed to him, "va'yeit shichma lisbol," he accepted upon himself the burden of hard work and toil.