Next time a client or stakeholder wants to know how long something will take, or how much it will cost…
Lead with the worst-case scenario. Tell them all the reasons it will take so long and/or cost so much.
Wait for them to react. Then, tell them the best-case scenario.
In our desire to please, we’re often overly optimistic. This means the other person benchmarks your time or cost estimate against what’s in their mind.
It’s better for you that they benchmark your estimate against the worst-case scenario. It’ll seem more palatable to them.
So stop being so quick to please. You can still be optimistic. Just make sure you’re pessimistic first.