The Grateful Slave
One day a good-natured king gave a rare and beautiful fruit to a slave, who tasted it and thereupon said that never in his life had he eaten anything so delicious. This made the king wish to try it himself, and he asked the slave for a piece. But when he put it into his mouth he found it very bitter and he raised his eyebrows in astonishment. The slave said: 'Sire, since I have received so many gifts at your hand how can I complain of one bitter fruit? Seeing that you shower benefits on me, why should one bitterness estrange me from you?'
So...if you experience suffering in your striving, be persuaded that it can be a treasure for you.