Habits get sold the same way supplements do, and usually with worse sourcing. Half the famous numbers in this area turn out to be product names, book titles or round figures somebody liked.
So we check them the same way we check everything else: read the primary research, rate the confidence, trace where the claim came from. With one extra column that health writing almost never gives you — what the habit actually costs you. A real effect that eats forty-five minutes a day is a different proposition from one that takes three, and you cannot judge the first number without the second.
Nothing on this page is for sale, and nobody pays us to reach a conclusion.
Body
What it does to your physiology — how you move, sleep, eat and recover.
supported7,000
steps a day, where most of the benefit has already landed
Time
About 30 min of walking on top of a normal day
Money
None. Your phone already counts
Difficulty
Low. No equipment, no technique
unsupported2.5 L
the 1945 figure — including the water in your food
Time
None. You are already doing it
Money
None, unless you buy it bottled
Difficulty
Low. Thirst does most of the work
preliminary0.37
the risk of sudden cardiac death, at 4-7 saunas a week
Time
4-7 sessions a week, 19+ min — the dose studied
Money
A gym membership, or thousands to install
Difficulty
Low, if you have access. Access is the cost
Mind
What it does to your attention and mood.
preliminary21
people randomised to box breathing in the only head-to-head trial
Time
5 min a day — the dose actually tested
Difficulty
Low. No equipment, nothing to learn
unsupported15-25 mg
of cortisol given daily to people who have too little
Time
None. There is no procedure to perform
Money
$1.41 a click for the search term alone
Difficulty
You cannot remove a hormone you need
unsupported0.10
how tightly cortisol tracks BMI, over 146 cohorts
Time
None. There is nothing here to do
Money
Cortisol supplements carry a $2.24 cost per click
Difficulty
You cannot act on a one percent association
supported87
randomised trials, every one against an active control
Time
Unknown. The trials were too varied to give a dose
Money
None required. These are practices, not purchases
Difficulty
Moderate — the effort is the intervention
unsupported1.01
what sleep hygiene adds inside CBT-I. 1.00 is nothing
Time
Minutes to read. Nothing to practise
Difficulty
Low. Nothing to schedule or stick to
Meaning
Purpose, belonging, connection. The evidence here is nearly all observational, because you cannot randomise a reason to get up — so the tiers run cautious even when the studies are enormous.
preliminary0
studies of Loma Linda, one of the ten Blue Zones
Time
Nothing was assigned or tested. It is a description
Difficulty
Climate, genes and isolation cannot be adopted
supported1.5x
the risk of dying, for people who said they had no ikigai
Time
Nothing to schedule. It was never tested as a practice
Money
None. Nobody sold anything to the people studied
Difficulty
Unknown. No trial has tried to create it
Every habit above is also filed in the full claim index, alongside everything else we have read.