Do you mean as a priest on the altar presiding over Eucharist like I was called by God when I was 16 to do?  Our church laws not allowing women ordination stand in my way.  Also because the U.S. has so many deacons, (18,000 is the correct amount for the US from the stats I saw last year) most works other than teaching Faith Formation, or being Eucharistic Minister or Lector are not available to laity in most churches.  I do lector still & serve as a E.M. and lead a Charismatic Prayer Group & until this current year taught Faith Formation at my parish.  However, when you are called to be a priest, the ache to hear confessions, preach during mass, proclaim the Gospel during mass, lead a flock, preside over Holy Eucharist never leave you.  This ache leads you to fight for change which I am doing too, and as I believe God wants me to do in an effort to cast out this hatred of women from our church. 

For many laity, once they are shoved aside after volunteering, they stop volunteering.