I just turned 50 - here are 10 life lessons I wish I'd learned a decade ago

Sending your kids off to college can be traumatic, but becoming an empty nester is also an opportunity. Couples may wake up to the reality that it's just the two of you again.

Reconnect to a time when you were someone other than "mom" and "dad." The door may be closing on a day-to-day routine revolving around kids, school, and family activities, but having the time to pursue your own interests and rekindle your romance can set the stage for decades of happiness to come.

There's a popular saying that summarizes this one pretty well (and I'm paraphrasing): When you're 20, you try to sneak into parties; by your 40s, you try to sneak out.

When you drink later in life, you'll likely get drunk on fewer drinks, and the hangovers are worse. Blame biology: after age 40 your liver becomes less efficient at processing alcohol, making your tolerance lower, and your body retains less water, making you more prone to hangover-inducing dehydration, according to The Wall Street Journal.

One of the big changes I made in my 40s was trading in a big house with a pool for a small one on a lake. The latter has plenty of living space but is far easier to keep clean and organized — and the lake doesn’t require any maintenance at all.

Simplifying has been so calming that I sometimes wish we had kept the starter home we had in our 20s rather than buying into the typical suburban big-house dream (and burdens) in our 30s.

One of the big changes I made in my 40s was trading in a big house with a pool for a small one on a lake. The latter has plenty of living space but is far easier to keep clean and organized — and the lake doesn’t require any maintenance at all.

Simplifying has been so calming that I sometimes wish we had kept the starter home we had in our 20s rather than buying into the typical suburban big-house dream (and burdens) in our 30s.

One of the most important things I realized in my 40s is that there are a very limited number of people in your life who truly love and care for you. Those people are irreplaceable.

Negative people, on the other hand, aren’t just expendable — they need to be excised from your life, both personally and professionally. If part of growing older is learning to deal with having less energy, you certainly don't need to be around dour, life-draining people.

We've all heard the sad story of the guy who works all their life only to drop dead a week after retirement. Too many 40 year olds think the best years of their life are in the past. I was one of them. It's the worst lie we tell ourselves.

In my 40s, I learned rock climbing; my wife ditched her hectic but ultimately unsatisfying career as an attorney to go back to school for a psychology degree. The truth is that we're never too old to learn something new, or to experience new things.

I spent decades making choices in my life not because they were good for me or my family, but because I "felt bad" about letting down other, frankly less important people.

It took me until my mid-40s to realize that the real obligations were the ones closest to home. Beware of knee-jerk responses: There's nothing quite so old as being "set in your ways." Whether you say yes or no to something, make sure there's thought and intention behind it.

I spent decades making choices in my life not because they were good for me or my family, but because I "felt bad" about letting down other, frankly less important people.

It took me until my mid-40s to realize that the real obligations were the ones closest to home. Beware of knee-jerk responses: There's nothing quite so old as being "set in your ways." Whether you say yes or no to something, make sure there's thought and intention behind it.

If you're doing life right, you're learning as you live. Some of that comes from loss and the inevitable mistakes you’ll make as a parent, spouse, and friend. If you’re lucky, you'll come through it with a better appreciation of what you have and less concern about what you don't.

I’m happy for the wisdom I've gained by age 50, but could have prevented a lot of pain if I had learned to be a little more grateful a decade or so sooner.