Pushing your muscles to complete exhaustion feels way harder than stopping just before you can't do another rep—this extra effort might make you more tired and less likely to stick with your workout routine.

When you exercise until your muscles can't do any more reps, you feel much more tired and uncomfortable compared to stopping earlier, no matter how heavy or light the weights are.

If you lift weights until you can’t do another rep versus stopping before failure—while doing the same total amount of work—you’ll feel more tired and more worn out during the workout, especially if you’re a regular gym-goer.

If you're new to lifting and using light weights, you need to push your muscles until they can't do another rep to grow them bigger—otherwise, even doing more reps won't help.

If you're lifting heavy weights, you don't need to push to absolute exhaustion to grow your muscles—stopping just before failure works just as well, as long as you're lifting heavy enough.

When young guys who don't work out do leg exercises until they can't do any more for 10 weeks, lifting lighter weights and heavier weights both build muscle about the same amount.