Choosing A Profession

Whoever discovers within his personality and nature an attraction to a particular trade that his body is fit for and can endure its difficulty, should pursue it and make it his means of earning a livelihood, accepting its sweetness and bitterness. Let him not be discouraged if his income is denied him on some occasion; rather let him trust in G-d , that He will provide him with his livelihood all his life.

(Chovos HaLevavos, Shaar HaBitachon, Perek Gimmel)