starts at home: around the table praying grace -- at Mass on Sunday -- in the Confession line -- saying night prayers -- praying with your kids to do their best and practice good sportsmanship before the big game, etc.
If you love your children, let them know the faith is serious to you. And may God bless you with the grace to make your home a little domestic church where God is always first. Faith doesn't just happen. If you don't give the example and the verbal encouragement, your children are likely to fall into the statistics of lapsed Catholics later on. How will you feel on Judgment Day if God shows you all the generations of lost Catholics because you failed to do your best to pass on the faith. You are that vital, Dads!