Things/habits that have actually saved me money, but may not be for everyone. Saving money is not the reason I do them, but just a side-effect.
1. Went vegetarian. The shopping bill dropped when i started buying chickpeas, lentils, beans, tofu etc., cooking veg lasagne, rice, pasta etc. Meat is expensive.
2. Bought an electric car. Traded in my old i10 for a Volkswagen e-up. It is charged on night rate electricity and costs a fraction to run rather than the petrol i10, which was fairly frugal to begin with. '09 i10 was due replacement anyway after 11 years. Between what I bought it for (7k)and the trade in (1.5k), it had cost me €500 per year.
3. Cycle to work and shower at work, get the health benefits and free showers.
4. Bought a rice cooker, cheap €40 one. We had been using those convenience microwave rice packets for 2. €2 each, which is dearer than a kilo of rice. Pop the rice cooker on, go for a walk, and you then have perfect rice when you get home. Add it to one of the defrosted veggie meals from batch cooking and you're golden. I know you can cook rice in a pan, but the beauty of the rice cooker is you can leave it alone. It will cook it and keep it warm.
5 Learn to cook. Batch cooking pasta sauces and Indian meals is easy and cheap. Freeze single/double portions for later use. Making a big saucepan of minestrone or mushroom soup is a doddle, and much cheaper, and gives me/us soup for a week.
None of these have made my life any harder.
And one habit that would save money, and probably improve my health, which I may do in the future - give up alcohol. That is definitely a money-pit. I don't drink a lot, but it has a noticeable affect on my wallet and waist.