The 22nd Amendment to the Constitution limits an individual to two four-year terms as president. Part of the rationale behind this was that the office had become too expansive and powerful for a single person to bear such responsibilities. Recent decades have shown that the second terms of presidents have not nearly been as successful or productive as prior years. Also it has increasingly become unseemly for an incumbent to run for reelection by offering policies to select voting groups to curry favor, such as lower interest rates, subsidized health care, debt forgiveness, draining the Strategic Petroleum Reserve and industry-specific protective tariffs.
This can simply be solved by allowing only a single six-year term for the presidency, without permitting midterm successors to run for election. This would also have the benefit of thwarting ambitious politicians from seeking the office of vice president as a stepping stone and allow them to concentrate more on their role of leading the Senate. Former presidents would be free to run for legislative offices or be nominated to judicial courts, but could not serve further in the executive branch of government.