A burden is something carried in a sea-going vessel (Acts 21:3). God’s people carry burdens in their earthen vessels (2 Corinthians 4:7). The use of this word in connection with a ship’s cargo teaches us that a burden may weigh down a man, but that he is well suited for the purpose of burden bearing. In fact, for a ship to sail without a burden would be very dangerous. It needs to sit low in the water or it cannot be rightly governed. When a ship has no cargo, its hold will be filled with ballast to ensure that it does not sit too high in the water. This elevated position would cause it to fall over, so it is deliberately weighed down for its own safety.
Thus, every man has burdens and though some may help him carry them (Galatians 6:2) none can, or should, remove them (Galatians 6:5).
It is often said by preaches that Jesus will take away one’s burdens. This is not true. He will make that burden light by assisting us in carrying it (Matthew 11:30) but He knows we cannot sail safely without a burden.