Presidential age upper limit

[Angrboda]

The Constitution requires a President to be a minimum of 35 years old, yet has no maximum age.

Could Congress pass legislation to effect  a maximum age without having to pass all the hurdles of an amendment? Would it have to be another amendment -- and if so, what do y'all think of its likelihood of passage? How would you urge your congresscritters to vote?

That would probably be considered age discrimination, especially by an elder congress. However I'm not opposed to having a law for independent/bipartisan mandatory psychological testing prior to running for president.

Make it a yearly requirement for candidates and sitting presidents.