Maslow's Hierarchy of Needs
Maslow developed a theory of motivation in 1943. It remains, in my mind, as the most straightforward and usable model of motivation to this day.
I wouldn't suggest it is perfect, but I haven't come across anything better.
His theory suggested that people are always wanting and what they want depends upon what they already have.
Their wants can be arranged in a series of levels. When they have achieved their wants in one level they will move on to want what is in the next level.
Maslow suggested 5 levels:
These would cover our basic needs, the desire to satisfy hunger and thirst, the need for oxygen and sleep amongst others.
These could cover the need to feel safe and secure, be free from pain and threat, the need for predicatability and orderliness.
The need for a sense of belonging and friendship.
This would include the need for self respect and self confidence together with the desire to be recognised by others.
Self actualisation needs
This covers the need to achieve what you think you are capable of achieving whether that be a physical act or a state of mind. This is perhaps the least clear of the stages.