Due to failing healing and reaction times, I am seeking a little advice.

I (sadly) only ride XC now. Occasionally though, enthusiasm exceeds ability and I find myself nursing shredded shins/knees.

Aside from recommendations on learn-to-ride schools, could you please suggest suitable knee/shin guards. Priorities:
1 - Comfortable on longer XC rides
2 - Cool & Light
3 - Discreet (Not looking like I think I ride DH)

Tips (if acceptable by this site) on where to purchase (ideally online) would be great.

Cheers.