If we look at average people, most people want things such as “security”, “money”, “fame” among very many things. But here’s the problem: your team members are individuals, not average people. There’s no such person as “average person”. Sure, some of them probably will say they want “make great games” or “enough money to pay the bills”. That still doesn’t mean they wouldn’t be individuals who want different things.
As a producer, it’s your job to find out what motivates your team members. If one has need to see his ideas in the final game – then you’ve just found a great way to motivate that person: simply use some of his best ideas and implement them in the game. If one guy has need for fame, then showing his name in the credit list and mentioning him in public is great way to motivate that guy. I’m not saying this as a way to “trick” others to get them motivated. Trying to be cheap and cunning shows. I’m simply telling you that different people are motivated by different factors – and it’s your job to find the way to motivate everybody in the team. Sure, you can pick ideas on how to inspire your team members, but don’t just randomly try everything to everybody. Instead, treat people individually – and the way they’d like to be treated – and inspired.