I know there are a lot of Jewcers who had standard bar and bat mitzvahs, standing on the bima with the rabbi, saying a few blessings, making a speech about becoming an adult, and then sweating through a snowball on the dance floor while the adults drank too much and ate eggplant parmagiana. But if you weren’t part of the club getting Israel bonds and jewelry boxes/fountain pens in middle school, don’t think your chance is gone. My Bubbe had a bat mitzvah in her seventies (and everyone in my family sobbed through the entire ceremony. We’re softies). Many reform Temples now run programs for senior citizens who didn’t have a ceremony when they were younger, and have come to Judaism later in life. And you don’t have to be a senior citizen. If you’re 24 you don’t have to write it off. Know, first, that though we usually say that someone HAD a Bar/Bat Mitzvah, that is grammatically incorrect. You BECOME a Bar/Bat Mitzvah, which is to say, you become a son or daughter of the commandments. You’re just accepting the commandments upon yourself. Technically, even if you don’t have a ceremony of any kind, you still become one. But wanting to mark the occasion is totally reasonable, and you should feel free to ask your rabbi to help you prepare. 
Think it’ll be too hard to learn a Torah portion? Don’t sweat it. You can usually get by with just an aliyah, a short blessing you can easily get transliterated into Hebrew. Still feeling intimidated? Check out this article from the Chicago Tribune about a woman having her Bat Mitzvah 35 years late.
Bat mitzvah a journey of persistence, courage
Sue Saltsberg mimics her tutor's hand movements, gathering in the warmth and light of the Shabbat candles, the onset of Sabbath and its promise of rest.
But rest has never come easily to Saltsberg, an Arlington Heights woman with developmental delays. It seems she has been trying to prove herself since the day she was born, when doctors predicted the premature infant probably would die within 30 days. Now, at 47, she is preparing for the bat mitzvah ceremony that eluded her when she was 13.
Saltsberg's dream begins and ends at a Hoffman Estates temple, Beth Tikvah Congregation, which means "House of Hope" in Hebrew. It was Saltsberg's first temple as a child and the one she returned to in pursuit of her goal.
Each week, for 15 months, she and tutor Russell Vincent have practiced prayers and rituals for the Jewish rite of passage to adulthood she will celebrate Friday night.
You can do it, too!