Can anyone help me to understand ?

For years I have struggled with the Trinity. I think I can understand

the relationship between the Father and the Son and myself, but I cannot

grasp what is meant by the Holy Spirit. Is it my soul? Something that

is a faculty in me that I can access for help? The impulse to do good when I see need? What is It? Is it like the sunshine and shines upon us all or is

it inside myself?

Can anyone help me to understand ?