If a marketer is doing his or her job right, then marketing impacts consumer behavior by encouraging spending and swaying consumers' choices towards a particular brand. Marketing is actually a lot less important to consumers than one might think. By listening to marketing messages, the consumer has simply been persuaded, and not necessarily on the grounds of superior quality of the product.
Let's say for example a consumer was looking to buy a pair of running shoes. Thanks to Nike's ever-pervasive marketing strategies, just about everyone has heard the phrase "Just Do It". You may be in the shoe store looking at a pair of Nikes and a pair of similar, but far more affordable shoes. Thanks to Nike's marketing, you are likely to have a strong perception that Nike is a top quality brand, and choose to spend more money on buying the Nikes, even if the other shoes were actually more comfortable when you tried them on. By understanding the principles of marketing, you can avoid falling into this trap.