The first Avodah that was done in the Beis Hamikdash each day was Terumas Hadeshen. This was done before any sacrifices could be brought.
The Kohen designated by a lottery, would go up onto the Mizbeach and take a panful of ashes. He would bring the ashes down the ramp and place them on the side of the Mizbeach. These ashes would miraculously be absorbed by the floor of the Azarah.
In addition to the Terumas Hadeshen, the Kohanim would remove the excess ashes from the Mizbeach and take them to a designated place outside of the camp.
The sacrifices represent our spiritual growth and personal Avodah. But before we can engage in meaningful positive growth, we need to remove and deal with our negative baggage – our ashes. If we don’t, they will hold us back and create a blockage to achieving the growth that we seek.
The ashes placed beside the Mizbeach represents the negative baggage that we can deal with, overcome and transform.
But there may be things that we presently don’t have the ability or strength to deal with. Instead of letting them linger, we need to move them outside; to put them completely out of our mind and out of our experience, so that they too will not pull us down. They should remain outside until we have the strength to face them.
~ Based on Maamar Parshas Reeh 5714