Some people think about priesthood

"for a long time ~ even from youth.

"Some, after discovering the call, act on it right away.

"Others discover this call only later in life (for some, much later).

"A good portion of internal discernment involves reflection, prayer, and listening to God.

"Being involved in one’s parish, going to Mass regularly, receiving the sacraments, attempting some type of Christian or community service, and trying to live a good Christian moral life are just some of the ways that often help to bring one’s call into focus."

from the Vocations website
of the Diocese of St. Petersburg