20 Things Everyone Should Master by Age 40

How to End a Friendship

Be clear that you need distance, but avoid getting into specifics. You might say, "I've realized I need to take a break from our friendship. I have so much going on in my life right now, and I need to take more time for myself." Now isn't the time to try to change your friend or teach her a lesson. (If you believed you could see things the same way, you wouldn't be breaking up in the first place.) Above all, be sure you want to break up. It's unlikely you'll ever be able to return to the same level of intimacy.

—Irene S. Levine, PHD, author of Best Friends Forever: Surviving a Breakup with Your Best Friend

How to Stay in Touch

I don't often get to see or even talk to my closest friends from various stages of life (including the 16 who were my bridesmaids). But I stay connected with them—and the thousands of others in my BlackBerry. The key is managing your friending: The more organized and accessible your friends' information, the easier it is to stay in touch. So you have to set calendar reminders for birthdays (I do it for anniversaries, too), and keep your address book up-to-date. And when someone pops into your mind, let them know, even if it's just with a "Thinking of you" text. Don't let the moment pass; treat it as a reminder to reach out.

—Alexandra Wilkis Wilson, cofounder of the five-million-member Gilt Groupe; keeper of 16,500 BlackBerry contacts

How to Not Sweat the Small Stuff

The thing that's grand about spending your time thinking about the universe is that it makes you feel insignificant. I don't mean that in a bad way. If you understand that we've now discovered entire solar systems that contain planets similar to Earth, and that those are just the ones we know about, since most of the stars we've looked at are within about 300 light-years of Earth and the distance to the center of our galaxy is nearly 100 times that—then you realize that the laundry you've left undone and the dumb thing you said yesterday are about as significant as slime mold.

—Alyssa Goodman, professor of astronomy, Harvard-Smithsonian Center for Astrophysics

How Not to Embarrass Yourself at Karaoke

Warm up all day. Start by counting aloud when you wake. Later, laugh out loud; we laugh higher than we talk, so you'll be activating your upper register.

Lubricate your voice, especially if you're nervous (stress can dry out your vocal cords). Half an hour before you sing, eat a little bread soaked in olive oil.

Breathe from your diaphragm. You'll generate the air you need to produce a melodious tone. Inhale through your nose and push your belly button out. Exhale and let your navel go back in.

Feel free to change keys. Even the pros sing in a lower register when their voice gets tired.

Sing with joy, from your heart, and no one will care how you sound.

—Debra Byrd, vocal coach for The Voice and vocal producer for The Next: Fame Is at Your Doorstep

How to Make New Friends—at Any Age

I tell my patients, "Food, alcohol, and drugs are no substitute for a relationship." If you're lonely, do something about it. If you love the arts, take a course at your local community college. And if you can't find a place to get involved, create one. Besides seeing patients several times a week, I'm thinking about starting a group where immigrantsand refugees can talk about their feelings. It's important to be part of a community!

—Hedda Bolgar, 103-year-old practicing psychoanalyst and cofounder of the Hedda Bolgar Psychotherapy Clinic, in Los Angeles