~ from email ~
Although Jesus did not say how much we must pray, he referred to praying for one hour like it was no big deal (Matthew 26:40). Who knows how many “one hour” he prayed each day? And he sometimes prayed “all night” (Luke 6:12).
But why did you limit your question to what Jesus taught? The whole Bible is equally the word of God, not only the red letters. In one place, we see that someone prayed three times a day (Daniel 6:10, 13), and in another seven times a day (Psalm 119:164; this could mean numerous times instead of an exact number). Paul wrote, “Pray continually” (1 Thessalonians 5:17). Although there is no requirement in a legalistic sense, it would not be a strange thing to pray for one, two, five, or ten hours a day.
Spiritual diet is essential to determining one’s inner strength. Perhaps the most important advice is to avoid Reformed materials. The Reformed are exemplary on some things, but when it comes to the spiritual strength of the individual – personal spirituality or practical theology – their teachings are characterized by unbelief, false humility, and a defeatism that is based on a perversion of divine sovereignty.
Become established in the doctrines that the Reformed excel at, such as their soteriology and eschatology (even on these they have many flaws), then if you wish to build up spiritual strength, drastically reduce exposure to their materials. And stay far away from the Puritans. They are overrated. Their materials are characterized by soul-numbing tedium, legalism, unbelief, depression, false humility, unresolved repentance, counterfeit intellectualism, and destructive self-examination.
The Arminians are better at emphasizing individual responsibility in faith. Regrettably, this is because they have rejected the doctrine of divine sovereignty. Thus both the Arminians and Calvinists are unworthy representatives of the doctrine. The Arminians reject it to exalt themselves. The Calvinists hijack it to excuse themselves. Still, when we are talking about the spiritual strength of the individual, the Arminians are often superior.
However, only the Pentecostals, especially the Word of Faith, consistently affirm a spiritual strength that overcomes by faith, that effects victories and alters circumstances, instead of using God as a mere psychological crutch in the midst of defeat and suffering. Only the Word of Faith teachers take seriously Jesus’s teachings on faith, power, and miracles, and Paul’s teachings on our position and authority in Christ. All other Christians practically denounce them, and in effect declare that Jesus and Paul lied to us, and that the Bible is false.
When we are talking about building spiritual strength, wisdom, and inspiration by prayer, then there is no better way to pray than to speak in tongues. The Bible teaches that a person who speaks in tongues edifies himself in his spirit (1 Corinthians 14:4). The effect is beautiful, often astounding. Paul said, “I thank God that I speak in tongues more than all of you” (1 Corinthians 14:18). Cessationists also condemn the Bible on this matter, to their own destruction.