Of course we all have our limits, but how can you possibly find your boundaries unless you explore as far and as wide as you possibly can? I would rather fail in an attempt at something new and uncharted than safely succeed in a repeat of something I have done.
I have found that the greatest degree of inner tranquility comes from the development of love and compassion. The more we care for the happiness of others, the greater is our own sense of well-being. Cultivating a close, warmhearted feeling for others automatically puts the mind at ease. It is the ultimate source of success in life.
If you can force your heart and nerve and sinew to serve your turn long after they are gone, and so hold on when there is nothing in you except the will which says to them: 'Hold on!'