I've also been diagnosed with osteoarthritis in my left hip. Also in my right hip, both sacroiliac joints and lower lumbar area of the spine. All proven with x-rays. Arthritis in other areas, especially the knees also probable. But I'm 63 and had a life filled with trauma. You drew a bad hand of genetic cards apparently.
Prior injuries lead to arthritis. Much of mine was probably caused by climbing and weight lifting. You want to minimize impact and trauma. Keep your gym weights light and do more and slower reps. If you can't do 20 reps with the weight, it's too heavy. I've read that rowing leads to a lot of back problems, so I don't like that advice. I'd also be careful with skating, because you use the hip joint differently with that exercise and the motion gives me pain in my arthritic hip.
Replace one or two of your weekly runs with deep water running. I've used DWR during long injury recoveries and like to use it when healthy in place of Junk (i.e. recovery runs). It simulates regular running better than any other exercise, but is impact free. Road biking, or spinning in the gym, are also good alternatives. Hiking and walking are also good cross training substitutes. Hiking briskly up hills will give you a good workout.
I'm hoping to continue running, but it will be off road and probably limited to two or three times per week. Hopefully I can do 2 quality runs per week. My long run mileage will be cut back and the run supersized with hiking (no pounding).
In training avoid running down steep hills. On gentle downhills keep it slow, but with a quick turnover and short stride to avoid pounding. Land on your forefoot and flick quickly off the foot. Don't heel strike!!!!!!!!!. Also, avoid gnarly single track as it places too much demand on the hip (that's how I finished myself off~~long trail races). Stick to dirt roads if possible. Maintaining your form is of foremost importance, as is shoe selection.
I hope you didn't love running as much as me. I've at least had 30 years more than you. Good luck.