The Church encourages Catholics to receive the sacraments often and with great faith and eagerness because Christ instituted the sacraments to nourish Christian life.
Christ Himself made the sacraments the instruments through which He gives His grace to us. This is what we mean when we say that Christ instituted the sacraments. There are references in the Bible to Christ’s institution of Baptism, Penance, the Eucharist, and Holy Orders (cf. Matthew 28:19–20; John 3:5, 6:52–58, 20:21–23; Acts 8:14–20; Romans 6:3–4; 1 Corinthians 10:16–17; 1 John 1:9). The Church infallibly teaches that He also instituted the other sacraments.
Three of the sacraments, Baptism, Confirmation, and Holy Orders, produce in the soul a mark which can never be lost. This mark or character is a kind of badge of our membership in Christ, a participation in His eternal priesthood, by which we are dedicated to sacred worship. Baptism and Confirmation can be received only once. Holy Orders confers the grace of the diaconate, the priesthood, and the episcopate only once.
The greater the faith and charity we have when we receive a sacrament, the greater the grace that will be given us. We should not neglect this means God has given us to grow holy and pleasing to Him by sharing His divine life.