2.1 What is the FITT Principle?

F = Frequency

This is typically measured by how many sessions you complete each week. Ideal frequency depends on your fitness level, personal goals, and the type of exercise you are doing.

General guidelines recommend aerobic activity three to five days per week, strength training two to three non-consecutive days per week, and flexibility exercises like stretching at least three times per week.

Tracking how often you train is useful, but it’s equally important to monitor rest days to ensure proper recovery and reduce the risk of injury. For those just starting out, aiming for two to four sessions per week provides time for recovery, helps build consistency, and reduces the chance of burnout or excessive soreness. More advanced individuals may train five to six days per week, often using split routines or alternating training goals (e.g., strength one day and aerobic conditioning the next) to optimize results while managing fatigue.

I = Intensity

Generally, the harder you work, the greater the potential improvements, but also the higher the demand on your body. Understanding intensity and knowing how to adjust it helps ensure your workouts are effective, sustainable, aligned with your goals, and performed safely.

Intensity can be measured in a variety of ways:

T = Type

While exercise is often discussed in broad categories (e.g., cardio, strength, or flexibility), the actual type should refer to the specific activity or exercise you are doing within those categories. Simply saying “I do cardio” is far too general. The more specific you are when selecting your exercise type, the more effectively you can tailor your routine to meet your needs.

Your exercise type should match your goal. Want better endurance? Choose running, biking, or swimming. Want to build muscle? Use weights or bodyweight exercises like squats and push-ups.

Beginners should focus on simple, low-risk and accessible exercises like walking, bodyweight movements, and resistance bands. Individuals with experience and/or advanced fitness levels may choose to incorporate complex lifts (e.g., power cleans), plyometrics, sprints, and heavy compound movements that require greater coordination, strength, and training experience.

T = Time

For cardiovascular exercise, flexibility work, or other continuous movements, time is often measured in seconds or minutes. For resistance training and other related exercises, using seconds or minutes is not ideal. Instead, sets and repetitions (reps) are used to measure the total volume of resistance training, since simply counting minutes doesn’t accurately reflect how much work you’ve done.

For example, rather than saying you “did push-ups for 10 minutes,” it’s more meaningful to say you completed three sets of 10 reps of push-ups, because this provides clear information about the amount of work performed. That’s how volume and progression are tracked effectively in strength programs.

In some cases, especially with static exercises like planks, wall sits, or isometric holds, a combination of sets, reps, and time is used. For example, performing three sets of a 45-second plank hold is a common approach that blends both time and sets to track progress.

Beginners often benefit from shorter exercise durations and longer rest periods to allow for proper technique, recovery, and habit formation. Advanced individuals can typically handle longer sessions and higher training volumes not just because of their improved fitness, but because their bodies are more efficient at recovering and sustaining effort.