According to Biblical examples, being in the Spirit is a worshipful state in which any true believer - anyone who has come to saving faith in Jesus Christ - can engage with God. It's a focusing on God and HIs written word. It's a prayerful or meditative state of mind and heart. It's submission to the will of God according to HIs word. It's a humble, loving and repentant communion at any specific time, and it can and should be a way of life.