Tough life implies a hard and challenging life. Life does not run smoothly all the time. The phase of growth from child to adolescent and then finally into an adult is filled with experiences which have their fair share of joys and sorrows. The journey of life has its own twists and turns. A tough life is more challenging than an easy one. You need strength and peace of mind to be able to endure a tough life and face adversities or turbulent times. A tough life makes you hard and rock solid from within. You become adept and skilled in the art of dealing and facing challenges valiantly and eventually you can groom yourself into a stronger individual.
So while praying as Bruce Lee had once rightly remarked, "Don't pray for an easy life. Pray for the strength to endure a difficult one. "Challenges and the experience of overcoming them is what makes a man and moulds him into a stronger individual.