Hi I'm 15 years old and I'm interested in becoming a priest when I'm older. I was just wondering what age do you have to be to enter a religious order like the Capuchins? I know Padre Pio was 15 when he entered and same with St Therese of Liseux when she entered the Carmelites
Such young ages as mentioned are not currently favored. It is unlikely that you would be encouraged to join the Capuchin Order under age 18. You would be best to contact the Capuchins in your region. You will find links online. In this way you could find out the answers to any questions you may have and begin, if you wish, some contact with the Order through the Vocations Director. The website of the Religious Orders tend to share some of their basic spirituality in their websites, which gves some idea of their spirituality and life.
If you directly contact those that might interest you, you can receive accurate replies to any questions you may have.
May God continue to bless you. And may all the Capuchin Saints and Blesseds pray for you.