The human body has an incredible ability to adapt to the demands we place on it. Not all forms of physical training will yield long term results. For long term success your exercise routine needs to incorporate progressive overload. Progressive overload is the continuous increase of intensity or workload of training and is a key principle in periodization. You can apply progressive overload to any exercise, any workout, and any long term program.
If you exercise regularly you expect to see the results of your training. If you do the same routine every workout or every week you are bound to reach a plateau in your progress. A plateau is when you no longer make progress in your fitness. A plateau can happen for any fitness goal, strength, body composition, cardiovascular strength, flexibility, or muscular endurance. If you are doing the same routine time and time again you need to make some changes.
My first recommendation for resistance training is to add more weight. If you want to get stronger, bigger, or faster you need to go up in weight. I suggest starting with a 5-10 pound increase for upper body exercises and 10-20 pounds for lower body exercises. Initially you should expect to do less reps. For example let's say you can squat 10 reps of 135lbs. You then increase the weight to 155lbs and only get 6 or 7 reps. Continue training at 155lbs until you can get 10 and then increase again. Understand that the adaptations take time and you should not expect to be able to go up again for at least 8 weeks. You could even add weight each set and do fewer reps each time. Something like: 10x 135lbs, 8x 155lbs, 6x 175lbs, 4x 195lbs This is a great strength building technique by athletes who regularly test their one rep max. To apply progressive overload to training volume and muscular endurance/ hypertrophy start by adding reps and/or sets to each exercise. Count the number of sets and reps to determine overall volume. Then add one set at a time and train until you reach the adaptation. For cardiovascular training you can begin progressive overload by gradually increasing the frequency, duration, and intensity. Keep in mind the amount of time needed for recovery may also increase with high workloads.
A big mistake people and sometimes trainers make is progressing too fast. If you are still making gains at a specific weigh, training volume, or intensity it may be too soon to progress. Quality tracking and fitness assessment is necessary to measure the rate at which progress is being made. Again, if progress slows or stops it is time to increase the workload.