No pain no gain belief

I’ve just found out that there’s this deep-rooted belief that pops up in my brain each time I set a goal for myself: no pain, no gain. It goes like this:
1. I have to suffer to reach my goal or else it doesn’t matter
2. I can’t enjoy rewards, meaning anything at all, if I don’t reach my goal 200%
Of course, it’s not a very successful belief:
C – goal weight
T – no pain, no gain
F – aweful
A – I do my best to follow my protocol, knowing the consequences if I fail (self-punishment, beating myself up), I don’t celebrate when I accomplish a tiny goal, knowing that there’s more to come and I should brace myself for it
R – I neither reach my goal, nor enjoy my life – lots of pain, no gain
I was thinking that I could start thinking “I’ve created so much pain for myself that I could start enjoying life now!” but it doesn’t quite stick yet.
Any feedback would be much appreciated. Thank you!