"How did you tell your parents?"
There have been three stages in my discernment--if you care to call the first "discernment". It began when I was about seven; I had an enthusiasm for Orders, religious saints, and religious in general that waxed and waned from then until I was about thirteen. I did not have to tell my parents anything about my being attracted to the religious life, because hints of it were everywhere. It came as no surprise to them when, at thirteen, I announced I wanted to join a Third Order. Though it was the first time I spoke of moving beyond interest and actually doing something, it was still a much easier topic to discuss than religious life proper, Third Orders being for lay people. If I had to give any advice, I would say gradually let your parents know you are interested in the religious life. Especially if they are of a different Faith, or if you haven't ever shown an inclination toward it before. Chances are God didn't spring a religious vocation upon you; I would suggest not springing it on your parents. That's what Father Francis did...and it didn't turn out all that well...
The second stage was when I began to actively discern (I was sixteen). My Spiritual Director encouraged me to begin seriously considering actually joining an Order, and I began looking into Orders to join. It was no longer a matter of "if" but of "where" and "when". I did not sit my parents down and "lay the chips before them" at this point, but I should have. And my advice would be to do this, when you tell your parents that you are actively discerning. Schedule a dinner, clear an hour or two in the afternoon, sit down with them and just tell them you are seriously considering the religious life. Be certain to tell them *why* you are drawn to it. That, I think, is the most important part. They need, above all, to know what this means to you. They are your parents; they love you and want what is best for you. When they see that this is what you feel you need to do and that this is what will make you happy, they will come around eventually, no matter how averse to it they might seem in the beginning.
"How did your parents take it?"
A vocation is difficult to accept, especially if it involves religious orders and especially if it involves girls. A religious is not like a diocesan priest. More often than not, becoming a religious involves your child moving very far away, with stringent visitation rules. Parents struggle with letting their children leave the nest in the most normal of circumstances. It can be devastating when they realize the "they'll be home from college at the end of every semester" expectation is now "I'll see them twelve hours a year". Giving a child to God is big loss that can be difficult to cope with.
My parents handled the prospect rather well, considering. Oh, yes, I had to hear my mother joyfully exclaim how wonderful it would be if my brother became a priest even as she cried over my becoming a sister. There was an occasion when she compared my leaving and joining to my being dead. I have a friend who joined the cloister a while back, and her mom took the separation rather hard. Their experience, I think, scared my mother very much even though I made it clear my "cloisterphobia" would never allow me to join such a convent as my friend. But my parents never said that they did not want to me become a Sister. They never forbid me from discerning. They love God, and know that it means to do His Will with an open heart.
My parents and I never had any difficulty with the fact of my discernment. However, they did disagree with the way I went about discerning. Actually, they disagreed with just about everything in that respect. When I said I wouldn't be going to college, they began to wax eloquent on the benefits of a higher education. When I said I'd join right out of high school, they protested that I needed to "live first". When I refused to date, all of the previous rules ("you can't date until you are 18!") instantly disappeared. If my spiritual director said to do X, they would find ten people (named or unnamed) to advise Y. I felt guilty and indignant at their lack of trust in my judgment and my SD's, and they felt hurt that I didn't take their advice. It was quite a while before the entire matter was resolved, but it was resolved eventually, and I will not exaggerate it: it was never very bad. There have been worse cases, and better ones.
Parents are supposed to prepare their children to make life decisions, and one of the greatest decisions is Vocation. Parents, naturally, worry about their children making the proper choice. However, they cannot make the decision for their child; and it comes to a point when they cannot even help. The fact is, parents are involved. Their love, their attachment, their worry...though not bad things (they are good things, and necessary!) can cloud their vision. They cannot view the situation or their child's spiritual state objectively. Meanwhile, the child--confused and worried over discernment itself--wants to please his/her parents. S/he will feel guilty if s/he thinks she isn't doing what her parents would like her to do. S/he will feel as though she needs to do what they want him/her to. And sometimes, what the parents would like their child to do just isn't what is objectively best for the child and their relationship with God.
It goes without saying that it is good to love your parents. It is good to listen to them, to weight their advice, and to learn from their wisdom. But when it comes to your vocation and your relationship with God...that is between you, your spiritual director, and God; no one else.
A friend of mine gave some good concrete advice for dealing with conflict in the family:
"Pray for your mom. Don't try so hard to make her accept your decision. Do not try to defend your own. It will only cause grief and the only thing that helps this situation is time -- lots of it. Years of it. Instead, focus your attention on loving your mom with all your strength. She's likely thinking about loosing you every time she sees you. If she offers you a barbed comment about your future choice, or that you should be dating, give her a hug and say "thanks for the love" sincerely and without sarcasm. Then drop it. You want your last months/moments with your mom to be memories she can hold onto when she wants to call and hear your voice but can't, when she wants to visit but can't etc...... Most of all --do not feel guilty. You are not causing your mother pain by your decision - her own attachments are. (Don't tell her this.... her attachments are good attachments..... she should be attached! She's your mom!) Give your pain to Our Lady and ask her to love your mom with all She's got! Rest in the arms of your crucified Beloved. He understands."
Don't worry about telling your parents that you are considering the religious life. Your parents love you, and that love will carry through anything. If you are concerned about how to tell them, then ask your spiritual director about it, or someone who knows them and you very well. Every parent is different and so every one will take it differently. But it will all be fine in the end. If you trust in God, He will never let you down. Just pray, hope, and don't worry.
Off-Topic Picture. I like it.
(PS: for more than my limited experience, go to the Vocation Station to hear others' stories)