Prayer is one of your greatest assets for spiritual warfare. Many times we are weak spiritually because we are weak in prayer.
A mother was looking for her daughter, and she heard noise coming out of the little girl's room. She looked in and asked, "Honey, what are you doing?" "Oh, I'm just telling God that I love Him, and He's telling me that He loves me, and we're just loving each other." That little girl had the right idea about prayer!
I have read a lot of books on prayer. Some of the advice I like, some I don't like, simply because it induces a lot of guilt. John Wesley said, "I have a dim view of any Christian who prays less than four hours a day." How does that make you feel? Or this quote from Martin Luther: "I have so much to do today, I must spend the first several hours in prayer."
Much that I read doesn't encourage me in prayer, it makes me feel worse, as if prayer is meant to produce guilt. That's why I think a lot of Christians are scared of it. But Philippians talks about taking every care that you have and turning it into prayer and supplication, and the peace of God which passes understanding will rule in your heart, not guilt (see Philippians 4:6-7). As I see it, prayer is meant to alleviate guilt, not produce it.
Of course, once you discover that prayer is a privilege, the length of your prayer time will increase. You won't have to discipline yourself, "OK, 15 minutes today, and then 30 tomorrow ... " Once you discover the power of connecting with your heavenly Father, it will become natural for you to spend more time in prayer with Him.
Prayer is one of your greatest assets for spiritual warfare. Many times we are weak spiritually because we are weak in prayer. And many times we rely upon some formula in prayer instead of just absolute trust in Him.
James said, "The effective, fervent prayer of a righteous man avails much" (James 5:16). That's good news. And the example he used was Elijah, whom he called "a man with a nature like ours." Elijah prayed that it wouldn't rain for three and a half years, and it worked. Now if a man like you and me could do that, then we can take heart!
There's a great story about a puritan who was praying in a public assembly with a lot of people around. He was praying an eloquent, golden-tongued prayer: "O omnipotent, fearful, glorious ..." As he went on and on, a simple woman next to him got tired of it, and she said, "Would you just call Him 'Father' and ask Him something?"
It's not the time spent in prayer, or some formula, or the eloquence of your language that makes your prayer effective. It's the fervency of your prayer, and the rightness of your heart before God.