According to the PMBOK Guide, the project manager is responsible for managing the project team and ensuring that the team members are motivated, engaged, and productive. One of the tools and techniques for managing the project team is interpersonal and team skills, which include communication, conflict management, emotional intelligence, feedback, influence, mentoring, and motivation. When a team member feels demotivated and excluded from the team, the project manager should first use their interpersonal and team skills to speak with the team member and understand the root cause of their dissatisfaction. The project manager should also acknowledge the team member's contributions and provide constructive feedback and guidance to help them improve their performance and engagement. This will help the team member feel valued, respected, and supported by the project manager and the team. References: PMBOK Guide, 6th edition, pages 349-350, 355-356.