Yes, I fully agree. These determinants, as well as many others, can change the motivation to continue the implementation of a specific project by individual people forming the team of project implementers.
I think these changes are different among people and in my opinion various aspects such as: psychological, cultural, economical, social relationship and people's attitude toward these things can be effective.
Yes, I think motivation changes at different stages of the creativity and innovation process in a project. Sometimes you need resources to bring the creative ideas into an innovation that make require funding. Applying and gaining approval for a grant can boost motivation as you now have the means by which to bring your innovation to fruition. I also think as we get older, we learn from our past experiences or even vicariously from others, so the wiser we are can potentially influence our motivation to succeed at achieving our career goals.
Creativity and innovation are dependent on inner drive especially. Age may not count at all. To create, its talent, motivation, right resources and the creative environment to thrive. These are the main determinants.