Retirement planning is more difficult than saving for other goals in life because of the many variables involved, and that uniqueness is why investors should approach it more as an "art" than a science, says Gary Williams, author of "The Art of Retirement". Before haphazardly creating a retirement plan, investors should understand behavioral finance to better understand how our brains deal with money and markets, says Williams. He also says investors should know their own money habits when deciding whether to make their own plans, or have a professional guide them.

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