There are analogies for life within the art of Wing Tsun kung-fu. One such analogy is the idea of forward energy.
Martial arts analogies exist in other arts but Wing Tsun seems to have many, perhaps because of its concepts. To prevail in an encounter with an opponent, it can be necessary to maintain forward energy and forward direction. To stand still can be deadly to you. Forward energy and forward movement forces an attacker to spend time and attention to deal with you. In addition, it is far more difficult to stop, block or deflect an oncoming counterattack than one that stands still. A moving target is difficult. One that is coming right at you is worse.