You could try listening to others when they speak and making a mental note of whenever they use a cuss word. Keep doing this (especially with your friends) and eventually you'll start doing it to yourself. You'll begin noticing when you use a cuss word.
Try using different words as well. Replace one of your more common swears with a less intense swear word.
Lastly, think about when you are using these words. If you use them when you're frustrated or angry, focus on being less so. If you tend to use these words most of the time, ask someone to mention whenever you say a cuss word. Having them acknowledge it out loud to you can help make you aware of when you say them.
Hope this helps!