"Men ought always to pray, and not to faint" (Luke 18 v1).
We Must Pray
To not pray is to deny our dependence upon God and to behave like an atheist. "The fool hath said in his heart, there is no God" (Psalm 53 v1). One of the marks of such atheism in practice is "they have not called upon God" (Psalm 53 v4). To not pray is a great sin.
Prayer is an act of Worship and therefore to be directed only to God and not to men. The Lord Jesus quotes Deuteronomy 6 v13 in Matthew 4 v10. "Thou shalt worship the Lord thy God, and him only shalt thou serve." And we must pray to God as he really is, not our own imaginary idea of what we would like God to be like. We know what God is really like from the Bible.
"I am the way, the truth and the life: no man cometh unto the Father but by me" (John 14 v6). There is "one mediator between God and man, the Man Christ Jesus" (1 Timothy 2 v5).
Where must our praying start? It must start with seeking forgiveness of sins from God and we must seek it God's way. We must recognise that our need is real. Our sins are serious and deserve the wrath of God forever. This must be faced, or there is no possibility of forgiveness and a place in Heaven. Then we must ask for the forgiveness we really need and we must ask God to forgive only because of what Jesus Christ has done in bearing the guilt of sin on the cross. "This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners" (1 Timothy 1 v15). "Believe on the Lord Jesus Christ and thou shalt be saved" (Acts 16 v31).
Only if you have sought God's forgiveness in this way can you truly pray for anything else besides.
David addresses God, "O thou that hearest prayer" (Psalm 65 v2). God always hears those who come to him through the Lord Jesus Christ, though he reserves the right to decide how he will answer, since he knows best as the all-wise God.
Where he has explicitly promised something, we know he will fulfil his promises. Where this is not the case, we pray knowing he can give what we ask, but also saying, like the Lord Jesus in Gethsemene, "Nevertheless, not what I will, but what thou wilt" (Mark 14 v36).
So, for example, with recovery from illness. God has not promised always to heal every illness even if we ask him. Not all the Christians of the Apostolic age were martyrs, but none of them are alive today. Many simply became ill and died. Even when there were apostles, there were Christians who remained ill. The apostle Paul refers to Timothy's recurring stomach problems in 1 Timothy 5 v23, and also says, "Trophimus have I left in Miletum sick" (2 Timothy 4 v20).
The Church then and now is not illness free. Nevertheless, we pray that the sick will recover, knowing God can give recovery, but we submit to his sovereign good pleasure. He is still God after all, not us. He decides.
God will do all he has said he will, but men must not try to put words into his mouth. He will do all he has promised and he can do what he has not, when we pray believing these things, this is praying in faith. And the children of God know he will work all things for their good.
Do you really pray? Have you come to God through Christ and said "God be merciful to me a sinner" (Luke 18 v13). All real prayer starts here.