Genesis 4:12 - Sin deminishes success

When thou tillest the ground, it shall not henceforth yield unto thee her strength; a fugitive and a vagabond shalt thou be in the earth.

God cursed the fruits of Cain's labor because Cain killed Abel, his brother. No matter how hard Cain worked the ground it still wasn't going to yield up to it's potential. This was also the case for Adam and Eve, Cain's parents. They fell from God providing everything, to having to work for everything. Sin is sin and it's all relevant.

Genesis 2:15 - The consequence of sin

And the LORD God took the man, and put him into the garden of Eden to dress it and to keep it.

Work is work and most jobs aren't pleasant. In the beginning, however, man didn't have to work for food was available and free to eat. All Adam had to do was to dress and keep the garden. Work wasn't meant to be but rather it was the consequence of sin:

Genesis 3:17 - And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life.

For those that don't like their job - accept it, keep strong, have courage and continue pressing forward with the confidence that things will get better.