Both of mine are offline and involve something in an everyday space that others wouldn't understand the significance of or possibly notice at all
First, the Hash House Harriers, the self-proclaimed "drinking club with a running problem". It's fun seeing chalk marks on pavement and knowing that a hash had recently passed by, even if it's been some time since I've been.
Second, geocaching. Tons and tons of containers hidden around you that you might never see if not actively looking for it. It's always a blast running into another person suspiciously looking about under a bench or whatever.
I've seen a few people recommending calorie counting here but haven't seen anyone mention Macrofactor, which seems weird considering how often I see people recommending Kagi. I draw the parallel because, while it's a paid product, I find it significantly better than the competition.
I started using it at the start of the year and have had steady progress. Foremost, it is extremely snappy and easy to log food. The database is fairly expansive without having poor quality user submissions. The real win of the app is the feedback loop. Rather than estimating calories expended using formulas meant to be accurate across a population (but not necessarily accurate to each person), it uses your calorie intake data and your weight data to derive your expenditure.
This, to me, helps reduce the stress of tracking significantly. Reason being, if you habitually do not track something like small bites during cooking or condiments, the calculation will take it into account and reduce your calorie target accordingly.
It also doesn't take into account data from activity trackers. Instead, your exercise is essentially smoothed over the following weeks. It helps psychologically to break from "I exercised so I get a treat" mentality, where you 1: immediately eat back whatever you've burned (or more) and 2: are telling yourself a reward for good behavior is calorie-dense food.
The website has a lot of data driven articles.
It also has a bunch of neat graphs. Anyway. Would recommend it. Obviously there's a LOT of different ways to lose weight, but for me it starts with understanding what I'm putting in my body. Can't outrun a bad diet.