The phrase, get a life has become a part of the English language the world over. Usually it is meant offensively; that is, that the person it is aimed at needs to focus their attention on something else. You might tell someone to get a life after focusing what you consider too much of their time on your private life. It could also mean that the person who needs to get a life is preoccupied with tiny details that are not relative in scale to the size of a meaningless problem. For example, if a photocopier breaks and someone stresses over it, you may tell them to get a life.
But telling someone to get a life can also be taken seriously. If you take a step back, you may realize that the level to which you compare yourself and your life with others is overly-competitive. It may even develop into a keeping up with the Jones' mentality where you might not be happy unless you have the same material goods or lifestyle as others, with a spouse and "2.4" children. In response, it's often recommended that people should have their own goals and ambitions in life and should not be swayed by materialistic items that others have.
To get a life that makes you happy is arguably an entirely individualistic thing. It takes courage and perseverance to stride toward your own goals while others are simultaneously telling you how you should live your life. Many people will adhere to a life pattern that is based on their parent’s lives or on people's lives that they know. This is not necessarily a bad thing, but it may not be what is ultimately right for you or will make you happy.
If you feel you have extra time during your day with nothing to do, then maybe you do need to get a life in the loose sense of the saying. You may find it rewarding to engage yourself in different activities, such as taking a course in a subject that interests you. These activities may enrich your life, and you may meet others with similar interests to boot!
Life is filled with important moments from births to weddings to deaths. But there is also an awful lot of time to be filled in between these important events. Most people's lives are so incredibly busy that they may not even realize it. If you don't stop and take a look around at what is happening you may miss the most important moments.