when life gives you lemons make lemonade

When life gives you lemons make lemonade is an older idiom which refers to the fact that you should make do with what you have by turning it into something positive. For instance, in this example, someone is given lemons and although they may have not wanted them, they can still make lemonade with them. It is to say in life you may be handed something unexpected, but it doesnt mean it cant benefit you in some way.