Many people will have to live as a legal adult for up to 4 years under a president in whose election they had no say. Lower the voting age for presidential elections to one of the following similar options:
1] Those who will turn 18 at or before 11:59 PM on the middle day of the term of the president being voted upon
2] Those who will turn 18 before 12:00 AM Jan. 1 of the year in which the middle of the new president's term occurs (16 by Jan. 1 after the election, shortly before next inauguration day)
3] Those who will be 16 on or before inauguration day
This will ensure that those who will become legal adults will have a say in the president under whom they will be legal adults for half of a term or more.