God’s power is limitless, sovereign, and comes from His perfect will and character. From creating the universe with just a word to parting seas and defeating armies, God has proven His power throughout history (Genesis 1:1-3; Exodus 14; 2 Chronicles 20). God’s power is also seen through Jesus—healing the sick, raising the dead, calming storms—and is now at work in us through the Holy Spirit (Ephesians 1:19-20; Acts 1:8). Though God can do anything, He acts in ways that fulfill His will, and He invites us to seek that will through faith, obedience, and ongoing relationship with Him (John 14:14; 1 John 1:9). Even when we are weak, His strength carries us, and we can trust that He is working all things for our good (2 Corinthians 12:9; Romans 8:28). We can rely on God’s power to strengthen us in trials, guide us in truth, enable us to resist sin, and equip us to live boldly and faithfully for Him in every circumstance.
As Jesus' promise states, what we ask must be in accordance with His will. In order to be sure that we are in accordance with His will, we must continually be in a right relationship with Him. That means that we must continually strive to do according to what we know is His will and we must confess our sins as soon as we are aware that we have committed them. In the latter case, we are assured that He will cleanse us from all unrighteousness and restore us to a right relationship with Him (1 John 1:9). It also means that we must constantly seek to know His will. Jesus promised that the Holy Spirit, who will never leave us (John 14:16) and "will teach [us] all things" (John 14:26), and this includes what His will is. But not everything we want when we are in a right relationship with Him will necessarily be in accordance with His will. For example, Paul tells of a "thorn in the flesh" (2 Corinthians 12:7-9) that he was afflicted with. He prayed earnestly for God to take it away, but instead God told him, "My grace is sufficient for you, for my power is made perfect in weakness" (2 Corinthians 12:9). Paul did not know the will of God when he prayed, but God's will was made clear to him afterward. Then, based on the rest of the passage, Paul, who wanted the will of God, was not only willing to put up with the problem, but he rejoiced that he had the problem.
We know, from the word, that He "is able to do far more abundantly than all that we ask or think, according to the power at work within us" (Ephesians 3:20). In addition, we have faith, given from God, (Ephesians 2:8-9) to act according to that power so that "for those who love God all things work together for good" (Romans 8:28). Since God is the one who works all things for our good and He has the power to do anything, we can rely on His power in everything. If we love Him, are in a right relationship with Him, and ask according to His will, we can rely on His power in all circumstances.