Vishwamitra was initially a king who finally became a Brahmarishi like Sage Vasishta by his sheer willpower. The story has a few points that we may be able to apply in our lives.
1. Irrespective of all the odds that we face, determination (along with God's grace of course) is the only thing that that will make us successful
2. When we read the stories of historical or mythological characters, it is important to focus on the takeaway message. For example- You could look at Vishwamitra's story and think this person does not seem to be able to control his senses time and again. But then again, the right way of looking at it would be, no matter how many times he failed, he rose back up each time. The resilience of Vishwamitra is the key takeaway from this story.