Continue working towards a better future. Elect the local Berniecrats in your area, and change the system from the bottom up. I wasn't expecting him to do even this well, deserving the nomination after all the BS he and his supporters were put through. All Clinton had to do was not screw it up, and she did, hard. Being a Clinton had a lot to do with it of course. Clinton is in the awkward position of barely beating (and having to rely on shenanigans to beat) someone who didn't want to be president to the nomination of the party her opponent wasn't even a part of. That's how bad of a candidate she is.
Bernie didn't want the nomination or the presidency. He wanted to revitalize the leftward movement of the 30s and 60s, bring progressive politics back into vogue. He has absolutely accomplished his goals. There are more young people engaged than....dare I say ever before? If not ever before in percentage, at least in volume. He got a coalition of young people involved in politics and he has encouraged and provided the spark for the next generations to take back politics from the corporate politics it is now. He understood that this was a long march towards progress, not a revolution. A lot of his followers didn't, but now they are part of the new revolution in 4 years. The worst is yet to come, but this is not a pessimistic or painful thing. 4-8 years from now, after Hillary loses her reelection bid to whoever the (R)s put up, will be bad. But then things will get better. After that election, maybe even before, a lot of the Berniecrats will be moving up the ranks in the world of politics. He has planted the seeds of change, and in 8-16 years time we will reap the rewards. Eventually, he will be vindicated, and celebrated, when one of his charges, those who heeded his call to arms, takes the oath and swears in to the presidency. It will come, in our lifetime.