I had spine fusion 1 year back. What exercise. Shall I do?

Low impact. Low impact swimming recubent cycle walking no golf no racket ball.Best to work with therapist.
Isometrics. Depending on which level(s) of the spine were fused, i advise my patients to pursue core strengthening of those and adjacent levels thru isometric means and swimming. Try to avoid repetitive impact to or around the fusion so as to slow adjacent level degeneration.
Core exercises. walk,swim,bicycle avoid running, heavy weight exercises or impact sports eg: volleyball, basketball, football.