Ask HN: Most interesting tech you built for just yourself?

I, like probably most other people, tend to start a habit and then it quickly fades away, not necessarily due to lack of wanting. I find that I might want to start, for example, strecthing my hamstrings regularly, I do them for some days/weeks and then I forget some days, then forget some more, and then after a while I realise I haven't done any for months.

So I wrote a webapp that I usually myself constantly now, it's very basic. I enter a habit I want to keep up and then visit the site everyday and click the "done" button when its done. It also has a calendar so I can see how often I've been doing it because not every habit is to be done every day.

I started this for exercising but i'm not using it for very basic/stupid things. One example is cleaning my glasses. I would never remember to clean them and I'd occasionally realise I'm viewing the world through a layer of grime. I now click "done" every day and the world looks crystal clear.

I guess it's just gamified habits a little bit and its working really well for me. There's a ton of habit trackers out that but I never found anything simple and quick to use.