Replenishing energy entails different activities for different people. The most obvious difference in these activities occur between introverts and extroverts.
Introverts replenish their energy by being on their own, in their thoughts, or with a few select people with whom they have intimate sharing, deep discussions and throw ideas about.
Extroverts replenish their energy by being with other people, preferably larger groups, where they soak in social interaction and express themselves in various ways.
Recharging is necessary because we use energy in our day-to-day activities. Think of a phone battery. At some point, it has to be recharged to keep the phone working. The more often it is drained, the sooner this happens.
Some research has been quoted to say that it is more tiring for an extrovert to behave like an introvert than it is for an introvert to behave like an extrovert. Nobody really knows why but it essential to recognise who you are and how you best recharge so you don't eventually run dry.
As teachers, our energy levels need to be kept up. When we are low on energy, we become ineffective at our vocation and unpleasant to be around. Always set time aside for recharging and do not neglect the early warning signs of irritability, difficulty concentrating and a general feeling of dullness.