We talk about capacity like it is our end point, the amount that we are able to endure. It's our excuse to refuse more, because we are at our capacity we have no more to give. The definition of capacity is "THE MAXIMUM AMOUNT AN ENTITY CAN HOLD, RECEIVE, STORE, OR PRODUCE." That seems pretty limiting as far as growth goes. So how then does our capacity increase, I mean our bodies and our brain do not get bigger as we gain "capacity" for things we do.
The answer is TOLERANCE. Our capacities do not change but our tolerance does. We gain capacity by extending our tolerance, and through that we increase our ability to endure or produce, and therefore our capacity increases. This is a weapon that we have as individuals to increase our abilities no matter what they are or what they are for.
Think about it, how is it that someone from California is cold when they visit their family in New York, but someone from the Arctic can be in freezing conditions and be totally comfortable, or vice versa. Again the answer is that through tolerance they have increased their capacity for the cold or the heat. I experienced this first hand when we moved from the North to the South in the summer. The humidity and heat nearly killed me, and everyone laughed at me, but when winter came and they were bundled up I was comfortable in a light sweater.
Over the years though, I have become accustomed to the heat, and the thought of going back north in the winter terrifies me.