Every time you plug something into a power outlet at home, you fully expect it to work, without giving much thought to the inner-workings of it all. Plug in a small clock and it just starts working. Plug in a 
blender and it’s ready to go. The phone charger may not need as much power as the portable heater, but it all comes from the same power source nonetheless.
This is not an exact parallel, but consider the power source, into which “we plug,” every time we pray. Just as you expect that wall outlet to be there and ready to provide power at any given time, we approach God through prayer and expect that He is there and ready to provide at any given time. (Of course, that is what He has promised [Matt. 7:7].) As with electronics, some of our “needs” and requests of God may be small or may be large (in our estimation), but the power “into which we plug” takes care of every need regardless. (God takes care of our “big needs” and our “little needs,” as He promised to do [1 John 5:14-15; 3:22].)
We may not know all the “inner-workings” of prayer, but remember that God is in control!