1. Training regularly toughens your muscles and increases your strength.
定期锻炼会使你的肌肉变得更坚韧，增加你的力量。

2. Going through difficult experiences toughens a person's character.
经历困难的经历会磨练一个人的性格。

3. The harsh environment toughens the plants, making them more resilient.
恶劣的环境会使植物变得更坚强，使它们更具弹性。

4. Enduring hardships and challenges toughens a person's resolve.
忍受困难和挑战会使一个人的决心更坚定。

5. Facing criticism and adversity toughens an individual's mental fortitude.
面对批评和逆境会增强一个人的心理坚韧度。

6. Learning from failures toughens one's attitude towards success.
从失败中学习会让一个人对成功的态度更坚决。