I used to say several times, "I surrender". Particularly saying them in quick-succession so that my ego doesn't jump in with its distractions and objections.
But now I find, if I just intend not to control anything at all, and just to be 'aware of any attempts to control, this works just as well and even perhaps runs deeper.
With surrendering, I can surrender the surface layers of what my ego has been doing to try to control situations, and relax back into openness and willingness to admit the truth. But maybe this isn't a 'total surrender'.
By focusing on 'not controlling anything', this instead strikes right to the core of the ego, which is entirely founded on an attempt to control reality and God. If I am not controlling anything at all, then I am not going outside of myself, I am not engaging in non-acceptance, I am not caught up in ego dramas, and I'm not even creating the thoughts that come as the ways in which I think reality should be different.
Give it a try. I'm enjoying experimenting with this. Just let go of controlling anything whatsoever. Don't even try to control thoughts or to control your mind or ego. Just stop controlling.