With the help of an estate planning attorney, you can give the authority to a person or entity to legally act on your behalf, including managing your financial estate. A trustee has a duty to carry out the wishes and instructions as set forth in a trust document and is typically chosen by you during your estate planning process. A trustee can and often does manage your financial affairs during your lifetime, when you can longer do so yourself because of illness or other unforeseen circumstance. An executor is a fiduciary who carries out your wishes as expressed in your last will and testament, and steps into this role after you have passed. A guardian is a person or entity appointed by a court of law when you have been declared unable to handle your own affairs.  This circumstance usually arises if you fail to set forth your wishes in a properly executed estate plan. An agent under a power of attorney can also handle your affairs while you are living and has a legal duty to act on your behalf and in your best interest. This situation typically arises when you have failed to set forth a complete estate plan, but you have granted someone the power to legally manage one or more of financial or medical issues through a legal document called a power of attorney.