Problem when trying to upload program to Arduino

I'm using an Arduino Uno and I have a program written for it, but when I try uploading to my board I get this error:

avrdude: stk500_recv(): programmer is not responding

It'll do this for a while trying to upload but it never succeeds.

Here are my settings and I'm using a MacBook:

Board - Arduino UNO
Port - "/dev/cu.usbmodem143101 (Arduino UNO)"
Programmer - AVR ISP