Several studies reflect that human related challenges are heavily impacting the successful lean implementation in the construction industry. Hence, overcoming the human-related challenges is one of the most prominent considerations to successfully implement lean concept in the construction industry. Accordingly, the aim of this paper is to investigate the human-related challenges and strategies to overcome those challenges for the successful implementation of lean concept in large-scale contractors in Sri Lankan construction industry. The qualitative research approach was followed, while case studies were selected as the research strategy. Data was collected through in-depth interviews with fifteen respondents from three case studies and analysed using code-based content analysis with N-vivo 12 software. The study identified issues in human attitudes, unfamiliar with the new concepts, lack of knowledge, lack of commitment, unwillingness to adopt new culture, lack of communication, lack of networking and collaboration, lack of committed leadership as few of the key challenges for unskilled, craft, administrative & professional, and managerial level employees. Among the identified key strategies, introduce new rules and regulations, provide training and motivation, conduct CPD and workshops on lean, enhance communication circle and provide lean performance-based promotions for unskilled, craft, administrative, and professional & managerial categories can be highlighted.