The locomotive should manage it fine, after all they are designed to last many hundreds, if not thousands of hours of running. I'd give it a once over if I were you - are the wheels clean, commutator clean (if applicable to motor type and serviceability) pickups aligned properly, oil on all moving parts and gears, etc. This one is obvious, but I thought I'd throw it into the mix anyway. Make sure the loco can manage the load you are planning to put behind it comfortably, with little or preferably no struggle. Otherwise, more strain may be placed upon the motor, leading to accelerated wear and tear, or worst case scenario a burnout. Is the loco running in a continuous circle, or is it going from one end of a layout to another, then back again?