You don't have to be a manager or a team leader to motivate others. Offering a listening ear or providing words of encouragement can make a world of difference to your coworkers. Sometimes, just being a positive influence, representing them when needed and showing them you have their back can go a long way in displaying you as a clutch player.
If you have worked in a leadership role, think of ways you helped set clear goals or helped individuals cultivate a new skill. Clearly communicating the big picture to each and every member of your team is crucial for making them stakeholders. This involves bringing them into the fold, and not just telling them what to do, but why they are doing it and the stakes involved. Equally important is understanding the motivators of each team member when assembling your teams, and ensuring you are promoting their strengths when assigning tasks, and never setting them up for failure or exploiting their weaknesses. Giving them a sense of accomplishment is integral to motivating their drive towards success.