Your two levels fused in the ACDF (C5-7) were most likely already so degenerative (“The operative reported that the disc space for levels operated was virtually obliterated due to significant bone spur formation”) that it is unlikely the surgery would have hastened adjacent segment disease (ASD). ASD is both biomechanical (degenerative segments or fusion or both) increasing stress on the next segment and genetic (the reason your two degenerative segments became degenerative in the first place).
Discs are just like shock absorbers on a car. Since they are avascular (no blood supply), injury to the discs are cumulative. The more impact and stress you place on them, the more chance they have to degenerate. I would avoid significant impact sports (running, tennis) and moderate the sports you participate in (skiing soft snow and not icy bumps).
Dr. Corenman
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.