Grinston is a native of Jasper, Alabama, and enlisted in the United States Army in October 1987.

He devoted the majority of his time traveling throughout the army to observe training and interact with soldiers and their families.

He sat on a variety of councils and boards that made decisions affecting enlisted soldiers and their families and routinely invited to testify before Congress.

Grinston holds a Bachelor of Arts in Business Administration from the University of Maryland Global Campus.

[7] On January 1, 2024, Grinston became director and chief executive officer of the non-profit organization Army Emergency Relief.