Are we really going to accept a Trump presidency?

I am getting really concerned now. The Humans of New York open letter to Trump basically outlines how I too feel (https://www.facebook.com/humansofnewyork/posts/1207382856002479)

Thankfully we have the Electoral College, but I feel like we need to start taking the initiative to do what we can to stop Trump. It's shameful that he has made it this far and I am saddened about this. I am hoping you hackers feel the same.

What can or should we do?