Stamina usually has a physical and competitive connotation — those with greater stamina can outwork and outlast opponents. While stamina is the ability to sustain focused effort despite pain or discomfort, you should also think of it as the ability to stay true to your values and commitments — to hold fidelity to a worthy purpose — especially when it’s hard to do so. Stamina, in this way, is not just the thing you deploy to keep running when your legs have gone volcanic. It’s contributing as par...