The key point here is: imaginary work doesn’t count. Get to running code early. Or a rough interface. Or an outline of the copy. Whatever it is, the way to get uphill is to roll up your sleeves. Seek out the things that might go wrong and show evidence that the approach will cover them all. Then when you get to the top of the hill, your team can trust that the work is really going to ship as planned.
If you are services company and can follow this process, you will be rock star company.