Spending money when you're trying not to spend money sounds counterproductive; if times are tight, why buy more stuff? The thing is, sometimes spending a little money now can help you save a lot more money later. Yes, it may sound boring and sure, I'm acting like your mum right now. But think of it like this: a tenner might seem a lot to drop on a reusable water bottle now, but in the long term you're going to end up spending way more than that on bottled water. You can apply this mindset to anything.
It's a hard one to get your head around but once you crack it, your bank balance (and Future You) will thank you when rent day comes around. Because it all adds up.