I've been legally able to vote for 2 years, presidential elections don't matter due to the fact that if people want to pass bills/laws/etc it needs to go through a vote in the house/senate. And even if it is a good bill, if one is recommended by the democratic party, the republican party will be like haHAA fuck you, you're a democrat and I'm republican, I vote no and vise versa. Are either of them fit to be presidents? No. Does it matter who gets elected? No, not really.
The greatest impact from voting on the nation/you is voting for your local government such as the mayor, governor, and state legislature.