Pocket Squat

■ Built around the one exercise that matters most: the squat Most of your muscle mass sits in your lower body, and it is also the first to decline with age. That is why this app does not do push-ups or crunches. It does one thing: squats, done properly, kept up for good. Hold your phone (or wear your Apple Watch) and squat. The motion sensor counts every rep. No tapping required.

■ The 120-minute insight from modern health science Large-scale epidemiological studies, including research associated with Harvard T.H. Chan School of Public Health, have reported that people who do 90 to 120 minutes of strength training per week, such as squats, have a 13% lower risk of all-cause mortality compared with people who do none. Do nothing, and lower-body muscle naturally declines with age, quietly eroding your healthspan. This app is built to push back against that decline at an extremely low cost.

■ Raise the load effectively with Serious Training Mode Repeat the same number of reps forever and your muscles simply adapt. Turn on Serious Training Mode and the app judges the pace of every rep. Only reps done at a controlled pace of one every 1.5 to 5 seconds count as proper reps. Bouncing up fast, or resting mid-set, does not count.

• A set with 60% proper reps is a proper workout
• Get 3 proper workouts a day on 3 days a week, and your reps per set go up by 10% automatically Only people who earn it get more load, a little at a time, every time. It is the progressive overload a trainer would give you, in your pocket.

■ Sustainable and fun to keep up One set is 15 squats, about 30 seconds. No gym time required.

• Sitting alarm: get nudged at the interval you choose during desk work
• Scheduled reminders: on waking, at noon, in the evening, whenever fits your day
• Extended healthspan: after every set, see in real time how much healthy time you have added. Your effort becomes a visible asset
• Streaks and history: weekly, monthly and all-time charts with estimated calories
• 10 color themes: the app's colors and its Home Screen icon change together
• Apple Watch: count on the Watch alone, with records synced to iPhone
• Apple Health: every set is saved as a workout

Start investing in your lower body today. Fifteen seconds at a time can change your future.

—— Pricing: Pocket Squat is completely free. Every feature is available at no cost. No in-app purchases, no subscription.