Ignore for a moment the fact I have told you I have a black thumb, and think about the following:
You've planted a garden. Thinking of what you wanted to grow, you threw some seeds in the ground. But you didn't take the time to prepare the soil, or even find the right kind of seeds. As time passed you didn't water the garden often. The few times you went out to weed you were unable to tell the plants you wanted from the plants you didn't. As the growing season drew to an end you looked over your garden in dismay. The bounty you had anticipated was not there. The little effort you gave produced little results.
This passive way of gardening produces little, as does a passive approach to managing your finances. It can seem pointless at times to worry over every single penny in and out of your hands but failing to do so ensures that your financial dreams will be as disappointing as the garden mentioned above.