Also bc @hifibriguy reminded me of the research:
One study (DOI: 10.1002/ejsp.674) that looked at time it took for people to turn various health-promoting behaviors into habits found:
Habit development rarely actually reached 100% automaticity. (Note: “automaticity” is a measure of how automatic doing the behavior felt based on a particular self-report scale that goes from 0-42; I’m converting this into a percent to make it feel more intuitive. 100% would be a score of 42 on the scale and would mean it was entirely automatic, involving nearly no thought on their part, whereas 0% or 0 would be essentially mean there was nothing automatic about it, would feel very purposeful/intentional.)
Some people (nearly 15% of participants) literally NEVER developed the habit. This is defined as an increase in automaticity to reach at least 50% automaticity (21/42) *based on mathematical model* that spanned not just the few months of the study but went out much further than that. Meaning that likely, even with multiple MONTHS of intentionally doing a thing, 15% of people might not be able to actually turn that into a true habit.
Most people who DID develop a habit developed it in a “asymptotic” way (about 51% of total participants). Meaning, the automaticity of the habit felt like it was increasing rapidly at first, then tapered off, approaching but never quite reaching a theoretical “maximum” automaticity. (If you’re interested, of the other 34%, a little over half had no good model or pattern to their automaticity- not even a linear pattern. Also, almost 5% of participants did show an asymptotic relationship between days doing the habit and automaticity but did not develop automaticity above 50% and thus were not classified as actually developing the habit).
Of the people who showed this pattern, the average “maximum” was 83% (35/42). Meaning on average, most people weren’t getting truly close to 100% totally automatic- there was still some level of purposefulness and/or ease (or low amounts of discomfort) in skipping the habit here or there.
Habits took anywhere from 18-254 days (some of this is based on model) with an average of 66 days to reach 95% of this “maximum.” That’s averaging a little over 2 months but spanning anywhere from a little over half a month to a little over 8 months + 1 week. While exercise behaviors took longer (average about 91 days) to achieve than eating or drinking habits, this wasn’t statistically significant. This is a very large span and indicates overall that individuals may differ in how long habits take to develop, and some habits may be quicker or slower to develop (perhaps based on effort or difficulty of the behavior change).
And the best of all: missing a day here or there (as long as it was isolated/not multiple in a row) didn’t actually affect automaticity all that much. The following day might have had to be just a little more purposeful, but only a very small amount on average. Essentially, if you miss one Monday gym session, it isn’t damning. If you fall asleep before you can brush your teeth Thursday night after a shit day of work, you’re probably not gonna totally forget again on Friday.
I know all of that is a lot to get through but basically, about 15% of us probs won’t develop some habits even over several months, those of us who do develop habits don’t develop them as quickly or even as strongly as sometimes we are lead to believe, and “breaking a streak” doesn’t automatically mean a habit you’ve developed is actually gone.