A person who is trying to advance by their own methods is like a sail that is facing into the wind. It might seem that straight ahead is the most logical route, but in a sailboat that will never work because a sailboat is dependent on the wind. A sail facing into the wind whips back and forth violently as if trying to rip free from it's ropes and toss itself into the waves. It cracks like a whip, then swings the other way and cracks again. It does no good to anyone and, frankly, it is a bit frightening.
On the other hand, a sail that is turned entirely with the wind puffs up like a soft pillow and steadily pulls the boat along. The ride is very quiet, and can be very peaceful, but it is also a bit dangerous. The boat slogs up and down as the waves pass under it. If a large wave bears down the boat will have a very limited ability to maneuver and will likely take on a bit of water. I liken this to someone who is "filled with the Holy Spirit" in that he or she is getting plenty of Spiritual nourishment but then he or she is hoarding it. Yes, they are moving along, but they are still at the mercy of the waves because the waves are passing them up.
However, a well-trimmed sail on a tack is an amazing experience. As you pull in the sheets (ropes) the sail initially whips around a bit but the oscillations become faster and faster until the fabric is humming. The entire boat shivers slightly along with it. The hull rolls over onto it's side as the sail picks up the full power of the wind. The hull surges forward through the waves at a terrific speed, throwing spray into the air and leaving a wake far behind.
All of this speed and power come from the fact that the sail USES the wind rather than just trapping it. The faster air moves, the stronger it is. The pressure differences between slow and fast air are so great that they can hold a massive 747 in mid-air. A well-trimmed set of sails create a similar effect.
This is being filled with the Holy Spirit. It is the constant adjustment of the lines so that you are always taking in the full power of God's Spirit in your life- and then allowing it to flow through you for His glory. Worshiping, sharing, serving, teaching, praying- God did not give us His Spirit so that we could slog through life, rocked up and down by the swells. He gave us His Spirit so that we could turn into the waves and rescue the lost and drowning.
image by Jonathan Pompe- I lightened it slightly