It sounds like either you have many things running (that you don't realize are) that are draining it.... also. if you are doing anything that is say graphic intensive (some games, movies, etc.) that will drain it fast... and the battery may need replacing.
In the case of programs running, it is pretty simple to check and stop those that don't need to be running all the time.
In regard to games, well unless you are able to change settings for them to use less resources (and less power) there isn't much to do there.
Lastly, many times when batteries are getting ready to stop working/stop holding a charge, they tend to say they are 'fully charged' when they are only charging a small amount, which then drains quickly due to the battery not using all of its 'space' so to speak. You may want to look into replacing it yourself, or having someone do it for you, before it actually goes out completely.