A man's mind may be likened to a garden cultivated or uncultivated. The cultivated produce flowers & fruit, while the uncultivated produces weeds. A man must continually weed-out all wrong, useless, and impure thoughts and deliberately cultivate right, useful, and pure thoughts.
Thought and character are one, and character has a profound influence on the circumstances of one's life. If a man learns the spiritual lesson of his current circumstances they will give way to other circumstances.
As long as a man believes he is a creature of external conditions he will be buffeted by those conditions. When he practices self-control and self-purification of thought and remedies his defects of character, he finds that his circumstances will change.
The soul attracts that which it secretly harbors -- its loves and fears. The soul reaches the height of its cherished aspirations and the depth of its unchastened desires. Every thought-seed allowed to take root in a man's mind will eventually produce the fruit of character and opportunity and circumstance.
Good thoughts bear good fruit, bad thoughts bad fruit.