A completely different take on this phrase is that discretion means being discrete as in protecting people or information from exposure in some manner. If one is to be perceived as possessing valor by others, then they cannot express this by being merely brash and powerful.
Probiotics are essential (for at least a month or two after the antibiotics stop, depending on the potency) when you have had antibiotics to replenish the beneficial bacteria.
Probiotics are good bacteria that are the same as or similar to the bacteria naturally present in healthy bodies. For example, you normally have a thriving population of bacteria in your gut, which help you digest food. Probiotic supplements can increase your levels of these good-for-you microorganisms.