People shared their biggest regrets in life, and some of their answers are heartbreaking

Hindsight is 20/20, as they say, and it can often lead to regret.

Some people have the philosophy that everything happens for a reason, and there is no point in having regrets.

But for many of us, looking back on our lives can lead to lingering on one poignant moment or period when we wish we had done things differently That nagging question, "What if ...?," plays on repeat in our heads.

"This may sound a little melodramatic, but no matter how happy you are, at my age your regrets are countless," writes Quora user Gary Teal. "You have made decades' worth of little miscalculations you can't completely erase from your memory, as well as a number of big mistakes that made life permanently harder."

Vaughn Bell at Mind Hacks notes that there are two ways people frame their regrets: The things they did that they wish they hadn't, and the things they wish they had done but didn't.

"The difference between the two is often a psychological one, because we can frame the same regret either way - as regret about an action: 'If only I had not dropped out of school;' or as a regret about an inaction: 'If only I had stayed in school.'

"Despite the fact that they are practically equivalent, regrets framed as laments about actions were more common and more intense than regrets about inactions, although inaction regrets tended to be longer lasting," Bell writes.

Quora user Bradley Voytek points to a national survey about the regrets of a typical American, which found 13 common sources for regret. They are, in order: romance, family, education, career, finance, parenting, health, "other," friends, spirituality, community, leisure, and self.

Here are some of the most common regrets as chronicled by Quora users (answers have been edited for clarity):