Become fierce enough to act and disciplined enough to aim.

Two capacities are needed and most people are strong in one. Fierceness gets you to act, to move before you feel ready, to keep going when it would be reasonable to stop. Discipline decides where all that lands. On their own, fierceness scatters and discipline stalls, and the useful combination is having both available at the same moment.

Work out which of the two you are short on. If you rarely act, practise moving before you feel ready on something small. If you act constantly with mixed results, practise choosing the target before you begin, and holding to it.