珍惜:cherish/treasure
把握:seize
回忆:recall/recollect/reminisce
怀旧:nostalgia
纪念:in memory of/commemorate
虚度:waste/loiter/squander/idle away
流逝:time flies/ wear away
延迟:delay/procrastinate
转瞬即逝:in a blink of an eye
千载难逢:once in a blue moon
Seize the day.把握今天;
Time and tide wait for no man. 时光不等人;
How time flies!光阴似箭;
indulges in reminiscences of 沉溺于对...的回忆;
recollect past experiences or events缅怀过去经历和事件;
contemplate the future思考将来