The resistance started January 20. Six citizen activists with Democracy Spring, AllofUs, and Americans Take Action disrupted Trump while he took the oath of office, standing on their chairs and revealing a single word spread across their clothing: R-E-S-I-S-T. 

https://www.facebook.com/democracyspring/videos/618592765007396/

Trump enters office after the most undemocratic election in modern history. In the first presidential election without the full protections of the Voting Rights Act since the days of Jim Crow, over 800 polling places were shut down, early voting was slashed, and voter ID laws were in full force across the country. These tactics are used by Republican state legislatures to deliberately and systematically disenfranchise young people, poor people, and people of color — anyone who is likely to vote against them.
 
Trump is about to become President after over one million people were deliberately purged from the voter rolls by the “Interstate Crosscheck” program. Crosscheck was implemented by Republican operatives across 29 states, matching people with the same first and last name and simply removing them from the voter registration rolls without their consent under the pretense of stopping them from voting twice. What were the most targeted names? Jackson, Hernandez, Lee — Black Americans, Latino Americans, and Asian Americans. The fact of the matter is that real cases of voter fraud are statistically negligible. The lie that there are millions of Americans who vote illegally has been spread by Trump and the GOP to justify the widespread and racist voter suppression that helps get them elected. And beyond this massive racist voter suppression, an authoritarian foreign government interfered in our election to Trump's great benefit. 

Anyone who comes to power through such a corrupt, deeply-compromised election is by definition illegitimate. Trump has no authority, no mandate to govern, and is already wildly unpopular with the American people. 

We disrupted him today to make it absolutely clear that he will be resisted from his very first moments in office. His agenda will be challenged and obstructed by a growing movement that refuses to go backward, that refuses to let our democracy be torn down by greedy oligarchs and a cowardly commander-in-chief.

Only a massive movement of everyday people can challenge the most powerful person on earth. We are under no illusions that the political revolution we need will be easy or quick or certain. But it is necessary. If we hope to prevent nuclear war, halt catastrophic climate change, and provide some basic measure of dignity and well-being to all people in our country, we must help create that massive movement of civil resistance. We must forge ahead and not falter. We must fight together.

References:
Voter Supression: poll closures - The Nation
Voter Supression: VRA - The Nation
Voter Fraud Myth - Brennan Center
Interstate Crosscheck - Greg Palast 
Interstate Crosscheck - Rolling Stone