The amount of exercise that crosses over from healthy to harmful depends so much on age, nutrition status, health concerns, and what you mean specifically by 2 hours per day. Certainly being active for 2 hours each day can be wonderful, and many people in labor jobs such as construction, or instructors of exercise are highly active for many hours each day. Variety is often key, as a mix of cardio, stretching, strength training, balance, and coordination may be very healthy, while doing repetitive movement such as running or cycling for 2 hours each day 6 days per week will likely be wearing on the body very quickly–again, depending on age, nutritional intake, and health status.
I hope this helps!
Zoe