1. Explain what "spiritual disciplines" mean.
We need to demystify prayer, Bible reading and meditation for teenagers. Too many times when we speak of spiritual disciplines in a non-specific way, teenagers have visions of monks and monasteries. It seems and sounds like something people in castles on hills in Europe do instead of, well, your typical Christian teenager.
Being engaged in spiritual disciplines is basically being spiritually disciplined when it comes to absorbing the truth of God's Words deeply into our souls and psyche. It is two way communication between us and God. He speaks to us through His Word and the wonder of His creation. We speak to him in prayer and sing to him in "psalms, hymns and songs from the Spirit" (Ephesians 5:19.)
2. Show them how they can engage in these disciplines via a smart phone.
If we make time with God all about big books and Jesus journals then we may be missing many of our teenagers when it comes to spiritual disciplines. Show your tech saavy teens the many wonderful apps available for them to read the Bible, memorize and meditate on Scripture and journal their prayers to God. Don't fight the tech bent of your students. If you do, you'll sound like the priests who railed against the evils of the printing press centuries ago. Satan has used technology for years for his purposes, God desires to use it in the souls of your teens for holy purposes.
3. Teach them how.
In Luke 11:1 when Jesus' disciples asked him to teach them how to pray he used a short, pithy prayer (aka "The Lord's Prayer") that is a powerful guideline for interacting with God. Of course, like any alliterating preacher, I have developed an acrostic for it that spells out PRAY:
Praise "Our Father in heaven, hallowed by thy Name."
Request "Your kingdom come. Your will be done on earth as it is in heaven. Gives us today our daily bread."
Admit "Forgives us our debts as we forgive our debtors."
Yield "Lead us not into temptation, but deliver us from the evil one."
In the same way teach your teens, not only how to pray, but also how to worship, read the Bible for all it's worth, mediate on God's Word and engage in silent reflection.
4. Show them how.
Talk to your teenagers about what you've experienced during your own times of prayer and meditation. Even share with them your struggles with prioritizing it at times. Spend time in prayer together as a group. Go on a spiritual retreat with your teens and, while there, engage in these disciplines together and alone. Gather at the end and share what God is teaching each of you as a result of your times with Him.
5. Get your teens sharing their faith.
Now evangelism may seem like it's non-related to spiritual disciples but it's not. Evangelism feeds our spiritual disciplines and spiritual disciplines feed our evangelistic efforts. Think of Jesus in the middle of evangelizing prostitutes, partiers and the poor escaping to pray on a mountainside. His missional movements drove him to pray, to reflect, to meditate on God's Word and look to the for the Father for wisdom, comfort and courage. It will do the same for us and our teenagers.