Jennifer Lopez opened up about life, love, work, and keeping it all balanced as the cover star of the the December issue of Marie Claire U.K. And whether or not you're a fan of Jenny from the block, she made one particular point that we all need to be reminded of from time to time. Namely, know your limits — and while you're at it, take some time off.Lopez admitted that early in her career, she often pushed herself to the limit and sometimes went too far. "I learned a lot from that time in my life where I did overstretch myself," the singer and actress told the magazine.These days, though, she's more selective about how she spends her time. "I can handle it better because I go, 'No, I'm not going to work on that day,' or 'No, I am going to take those three days off,' or, 'No, you cannot schedule the there [sic],'" the "Booty" singer explained. "And you realize the sky is not going to fall, even though everybody makes you feel like it's going to."(Perhaps another implicit lesson here is that if you want to be an international superstar who's earned the ability to say no to certain scheduling suggestions, you'll have to pay your dues first. But we get where she's going with this.)Another little bit of advice Lopez laid down during the interview? Don't discount the presence of your best buds. Following her divorce from Marc Anthony in 2011, her friends were the ones to swoop in and help her push through the tough times. "I think I realized they were as important — if not more important — when I divorced Marc. I just realized that I had been through that a couple of times and there they still were. Like they say, men come and go, but my girlfriends are always there for me."Get more pearls of J.Lo wisdom over at Marie Claire U.K.