It might be time to consider taking your training to the next level. Changing the intensity of a particular exercise may be as simple as increasing the weight and/or number of reps and sets or it could be achieved by increasing the difficulty. You can boost the intensity of an exercise by progressing from a modified or beginner version of an exercise (i.e. push-ups from your knees) to an advanced or intermediate version of that same exercise (i.e. push-ups from your toes). Increasing the intensity too quickly can be counterproductive as you risk overuse injuries like tendonitis, bursitis and fasciitis. Your body needs time to adapt to new demands and requires ample rest and recovery between workouts.