a research essay about mental toughness and what is it exactly and how it can be developped and what is its concept also what enables this for young adults and what obstacles  do they experience and is there any gender differences between both male and female when it comes to be mentally tough 
mental toughness and resilience – Google Scholar 
A review and conceptual re-examination of mental toughness: Implications for future researchers (sciencedirectassets.com) 
What Is This Thing Called Mental Toughness? An Investigation of Elite Sport Performers: Journal of Applied Sport Psychology: Vol 14, No 3 (tandfonline.com) 
Mental-toughness-research-Key-issues-in-this-area.pdf (researchgate.net) 
The Concept of Mental Toughness: Tests of Dimensionality, Nomological Network, and Traitness – Gucciardi – 2015 – Journal of Personality – Wiley Online Library 
Mental toughness and athletes’ use of psychological strategies: European Journal of Sport Science: Vol 10, No 1 (tandfonline.com) 
Are Adolescents With High Mental Toughness Levels More Resilient Against Stress? – Gerber – 2013 – Stress and Health – Wiley Online Library 
Frontiers | Mental Toughness in Competitive Tennis: Relationships with Resilience and Stress (frontiersin.org) 
Are Adolescents With High Mental Toughness Levels More Resilient Against Stress? – Gerber – 2013 – Stress and Health – Wiley Online Library 
Developing Mental Toughness: From Research to Practice (tandfonline.com) 
Mental toughness: progress and prospects (sciencedirectassets.com) 
Dark and Strong?! The associations between dark personality traits, mental toughness and resilience in Hungarian student, employee, leader, and military samples – ScienceDirect