Kids make great prayer warriors and missionaries. Never sell them short (no pun intended), because of their height or age! In fact, here at The Waiting World, we can tell you from personal experience, if you begin exposing kids to missions when they are young, they will develop into more mature, caring, loving Christians more quickly than their peers.
By the time they are in high school, or, even in junior high, hopefully they will have opportunities to go on short-term mission trips. Upon high school graduation, we highly recommend they take a break between high school and college and do some sort of mission training and outreach program. After an outreach, students are often better able to discern what sort of collegiate or trade school program they want to pursue. They may select something that will help them in ministering to others.
We recommend Youth With A Mission (YWAM), because it is the largest mission training and sending organization in the world. (Admittedly, we haved served with YWAM for over 20 years.) After 3 months of intensive classroom, students then do a 2-3 month outreach, usually overseas with others from their Discipleship Training School (DTS). For more information on this, please contact YWAM Frontier Missions (ywamfm.org)
Finally, you don’t have to wait until kids are even in high school to start teaching them to prayer walk around your community! Here’s a great video for young children about prayer walking. Just click on this LINK