Consider:

"If you get handed lemons... make lemonade!" But lemons are not the only ingredient in lemonade; also required is water and sugar. If all you are handed is lemons, then all you can make is lemon juice, sour to drink. Sugar is what makes lemonade sweet. The adage assumes that you are handed not only lemons but also sugar, or that you had a sufficient store of sugar prior. Without sugar, if you are handed lemons, you simply cannot make lemonade.

And of course, it commonly occurs that, both figuratively and literally, there is no sugar.

Sometimes there is not even water.