The significance of having a "no-pain, no-gain" mentality lies in its reinforcement of the idea that effort is crucial for achieving fitness goals. This mindset encourages individuals to push through discomfort and challenge themselves, leading to greater strength, improved performance, and progress. However, it’s essential to balance this mentality with self-care to avoid injuries or mental exhaustion. Recognizing limits while striving for growth makes the "no-pain, no-gain" ideology beneficial when approached wisely.