TFS.
It's not hard to be positive, except on some days when it just doesn't work, no matter how hard you try. That's when 'going with the flow' helps. Just pretend you're a log flowing in the stream, let the water take you where it will.
'Coz what you resist, persists. So if you resist negativity it will come back more forcefully. Just make sure the stream doesn't take you to the ocean of darkness :P It is a struggle nevertheless.