How Hard Should You Train?

The Truth About Intensity, Reps & Results. By Dan Kennedy, trainer.

We’ve all been there. You walk out of a workout drenched in sweat, exhausted, and think, “That must have been a good one.” But was it?

As a PT, I see a lot of people working incredibly hard in the gym… just not always in the right way. Some will lift too light to make progress or finish at their allotted rep count when they’ve got much more left in the tank, whereas others will push so hard, it’s likely they’re sore for days. So, how hard should you train? It really boils down to three things: effort, intensity, and intent.

Intensity vs. Effort — What’s the Difference?

Effort is how hard something feels, whereas Intensity is how heavy or demanding it is compared to your maximum. To give you an example: you might feel like you’re working hard after say 20 air squats, but that’s low intensity. Do five heavy reps at 85% of your max squat? That’s high intensity — even if you’re not gasping for breath.

Getting this balance right matters because your body adapts to stress - not being exhausted. Too little, and you don’t progress. Too much, and you can’t recover.

“Training is stress; results come from how you recover from that stress.”

Training to Failure — Smart or Silly?

Training until you literally can’t do another rep: that moment of failure can feel like a badge of honour to some. It’s an approach my trainer advocates – he feels that you’re not pushing enough if you’re not doing it to failure, every time. But, training to failure isn’t always necessary or always helpful to progression.

When it can help:

• When you’re an experienced lifter needing an extra stimulus
• When it’s the final set of an exercise
• When you’re targeting small muscle groups (like biceps or triceps)

When it can hurt:

• When your form breaks down
• When you’re training the next day
• When you’re focusing on recovery or skill 

Most research shows you’ll get the same results if you stop 1–3 reps before failure…and you’ll recover faster, too. In a nutshell, you don’t need to crash the car to know you’re driving fast enough.

So, Just How Many Reps Should You Really Do?

It all depends on your goal: lift more for less if you want to get stronger, and less for more to increase your endurance:

So for most, finishing each set knowing they could do one or two more good reps, they’re right where they should be.

“If your form breaks, the set’s already over.”

Matching Intensity to Your Goal

For Strength:

• Lift heavy for low reps - around 4-6
• Take long rests, to give your muscles time to recover
• Keep your focus sharp and your form tight to avoid injury 

For Shape or Tone:

• Moderate weight for 8-12 reps
• Controlled tempo, especially lowering the weight
• Look to feel the muscle work; that’s where change happens

For Endurance or Fitness:

• Lighter loads, higher reps, or circuits
• Keep your heart rate steady, not spiking
• Prioritise movement quality over speed

So, different goals, different rules. The only constant? ALWAYS form first, ego last.

When to Train to Failure (and When to Stop Short)

The best way to think of failure is like a hot sauce…a little adds flavour, too much ruins the dish.

Use it sparingly:

• Final set of isolation work? Absolutely
• Every set, every session? Absolutely not

Ultimately, consistency beats intensity every time. You’ll make more positive progress doing solid sessions week after week than you ever will burning out on “beast mode” once a month.

Recovery Is Part of Training

If you’re going to train smart, then you’ve got to recover smart, too. Muscles don’t grow in the gym (although they might feel pumped at the time of working out as they’re engorged with blood) they grow between sessions.

• Sleep: 7–9 hours where possible
• Hydrate: It sounds basic, but dehydration kills performance
• Fuel: There’s a reason for the expression ‘muscles are made in the kitchen’. Make sure you get enough protein and don’t skip meals
• Move: Light walking, stretching, keeping mobile - active recovery keeps you supple

The Motion Labs Takeaway

Training to failure might make you tired. Training with purpose makes you better.

You don’t need to destroy yourself every time to make progress; you just need consistency, intention, and a plan that matches your goals. Whether that’s lifting heavier, building shape, or feeling more athletic, it’s about doing enough to create change…and recover enough to repeat it.

Here at Motion Labs, that’s our approach: train smart, move well, and feel strong. Every session is about progress, not punishment.

“You don’t have to crawl out of the gym to know it worked. You just need to walk out better than you walked in.”

Want to Train Smarter?

If you’re ready to upgrade your training and find your sweet spot between effort and recovery, check out our downloadable programs and coaching plans at motionlabs.co.uk.

Real science. Real coaching. Real results.