Guides · Health, fitness and habits
Health, fitness and habit guides
Counting reps, breaths and days is easy; knowing what the number means is the harder part. These guides explain the scales behind the counts, such as RPE and reps in reserve, the normal breathing rate for each age and the waist-to-height cut-off, and what the research says about how long a new habit takes, with each figure traced to the study or health body that published it.
All health, fitness and habits guides
Push-up test norms by age and sex, and why the tables disagreeGood is 22 to 28 push-ups for a man in his twenties and 15 to 20 knee push-ups for a woman, on the Canadian test. The full table, the rules behind it, the Army's 2-minute version, and what the firefighter study can and cannot tell you.Published · 13 min read
Normal breathing rate by age, and how to count breaths per minuteA newborn breathes 25 to 60 times a minute and an adult 12 to 20. Ranges by age from the source, why charts disagree, the thresholds that mean fast breathing, and what a 15-second count does to the number.Published · 14 min read
Reps and sets explainedWhat 10 reps and 3x10 mean, where 3 sets of 10 came from, and what the 2026 ACSM review changed.Updated · 9 min read
Track a daily habit streakWhy streak apps fail, and what a plain daily counter does better.Updated · 5 min read
Waist-to-height ratio: the half-your-height rule, how to measure, and the bandsKeep your waist under half your height. NICE's bands and who they apply to, the tape position three bodies disagree on, a ready table by height, and why sex-specific calculator charts are wrong.Published · 15 min read
RPE and RIR explainedThe 1-10 lifting scale where RPE 8 means two reps left, where it came from, what studies of 414 lifters say about guessing reps in reserve, and how to adjust the bar between sets.Published · 17 min read
How long it takes to form a habit, and where 21 days came fromThe 66 days is a median of model estimates, not a deadline, and the 21 days was never about habits. What Lally's study measured, the 2024 review, and how to track your own curve with a counter.Published · 16 min read
Box breathing: how to do it, how many rounds, and the evidenceFour equal sides of 4 seconds is the start, not the rule. How many rounds the trials used, what they measured, what they did not find, and who should ask a clinician first.Published · 16 min read
Other topics: counting and tallying, sports scoring and rules, writing and word counts, lab and field counts, prayer beads and crafts, or every guide on the guides front page.