Principles of Preserving Wealth The slideshow presentation that you would like to view is too large for your current screen resolution. Click here to view to view the slideshow at full resolution. Launch Presentation » Share | Have A Question About This Topic? Name Email Address Question Thank you! Oops! Related Contents When Do You Need a Will? When do you need a will? The answer is easy: Right Now. Put It in a Letter A letter of instruction provides additional and more personal information regarding your estate. What Is My Life Expectancy? Estimate how many years you may need retirement assets or how long to provide income to a surviving spouse or children.