Mindset change from Spender to Saver

As someone who lives her life from payday to payday with barely any money left at the end of each month, I realised I'm wasting so much money on impulse buys and needless junk.

I'm in a position to build up a savings fund but worried I'll blow it all on some large purchase further down the line that I don't need.

So I'm wondering how do savers build up a large saving fund without feeling the need to waste it, and also what do you eventually spend it on when you do splurge? Having money for the sake of it seems so strange to me and genuinely trying to change my mindset.