I'm going to end it with my personal trainer when I still have 4 paid for sessions left
Why do you want to end it early?
I don't have that much interest anymore.
It is okay to feel tired but you already spent the money so not going is just going to waste the money. It is not good to throw away money, people will think you are careless.
I just want to end the relationship since the personal training doesn't fix the problems anymore.
I still think you should finish. It's only four sessions and then you wouldn't be wasting money.