“I feel like I’ve exhausted all options, but my manager / coworker will not take “no” for an answer.”
When you feel like you’ve exhausted all options, often you are frustrated and maybe feeling disengaged. This state can keep you from seeing other alternatives.
Be curious: Seek clarity from the other person on their outcomes / goals. Explore their importance of them to this person. This discussion alone may provide insight.
Reach out: If you have not done so, seek a co-worker, mentor or friend for their outside perspective / expertise.
Reflect: Ruminate over answers to the question: “What would this look like if it were easy?” Then pursue the answers you came up with.
Dissect: Break the goal / deliverable into smaller milestones and focus on how to achieve each individually instead of the final end-state.
There are times when the answer will be “no” (or another less-than-desirable outcome). When this is the case, document each step you have taken (or theory you have tested), the people you have consulted with, and the result of each step / theory. Even if they dislike the final result, you will have shown that you have been diligent.
While you are responsible and accountable for having done due diligence, you are not responsible for their acceptance of what may not be possible right now.