I was a triathlete and marathoner in the early 90's until hip pain and the arrival of three children caused me to become less active, with most of my exercise then consisting of walking on the golf course 1-2 times per week. I had a right total hip replacement in November 2002 at age 42. My surgeon at the time did not recommend the re-surfacing. I can't complain. The surgery was a complete success with no complications and quick recovery. In July 2006 I started getting back on the bike for the first time in over ten years. I quickly became hooked again and now ride on average four days a week (more but its winter here), including road, MTB and fixed gear. I raced in a half-dozen CX races this year and had a blast. You should do great. I wish you best of luck.
Steve
Ellicott City, MD