It is that which cannot be sincere because it is detached from actuality. The following things will never affect sincerity: Drugs, Lack of Sleep, Fear, Searching, everything. Self actualization is what breaks down the barrier between reality and actuality. Acceptance of the self occurs on one's own terms. Reality is the level at which your self actualization exists.
If one has goals, one cannot assume the original goal will be still be relevant after the journey of pursuing said goal is complete. If life is about change, then shouldn't goals also change in the process of pursuit of the original goal? Yes. Conforming oneself to a specific A to B journey means that any information picked up along the way cannot affect the outcome. If B is the destination you choose to pursue at all costs, then the integrity of the steps that lead you from A to B are being compromised so that you reach B at any cost.
Stasis is simply waiting for change that you can detect.
Accepting that goals "simply change" and that's just the way it is isn't enough. Using your awareness to justify that "goals change" means piling on new data in a specific way so as to justify the fact that initial goal B is no longer the destination. If one starts at A and plans to make to it B, but then C becomes the actual end to the process, then the guilt from not achieving B can be suppressed by justifying that B is no longer relevant because goals "simply changed". The new goal is C occurs because all the information gathered after leaving A has pointed in C's direction. However, once you are aware of what you think the outcome of C is, C's actuality is compromised. Sincerity is degraded. And C becomes an Idea, not actuality. You see what you wanna C.
Let go. There's no justification for your existence that will not come at the expense of what you gave up. No one gives up anything. It simply is at all times. Trying to manipulate it will leave one inclined to believe there is control. Change is. You change. It changes. Goals are estimations of self-actualization. Lack of sincerity is a by-product of assuming control, even if that control is declaring there is no control.
Only this moment. Is. Was. Isn't. dot. dot. dot.