Please choose the correct ending to complete the given sentence: Sports and Fitness: [header] How to gain more muscle mass and strength [title] Monitor your progress. [step] As you start gaining strength and building muscle, keep track of how much weight you gain, how much weight you can lift, and what exercises you do from week to week. This will help you figure out what works for your body and what doesn't, and keep you from getting into a workout rut.

Ending1: [substeps] If you find that a certain muscle group doesn't seem to be making significant gains, switch up your exercises to see if something else works better. Alter your diet as necessary to help you lose fat and gain muscle. Ending2: [substeps] As you increase your weight, you'll begin to see improvements. In fact, you may notice that you're exercising significantly more evenly lately. Ending3: Some things to watch for include : [substeps] Increase your impact. If you're in the gym you should aim to be at least twice as heavy at low impact intervals because adequate exercise (e.g. Ending4: [substeps] Let your body know that if you want to lose a pound (or more) of weight, it needs to come from within. You can't lose it too fast.

Answer format: ending1/ending2/ending3/ending4