How do I fix my posture?

[Jarno]

My posture is genuinely horrible but my body apart from that is good I go to the gym aswell and do some dumbass stretching routine for posture but it ain't doing shit what do I do?

 

[RetaRetaReta]

My posture is genuinely horrible but my body apart from that is good I go to the gym aswell and do some dumbass stretching routine for posture but it ain't doing shit what do I do?

show the posture

 

[Jarno]

show the posture

I can't take a picture that well because when I think about it I subconsciously fix it but my neck goes forward and my shoulders round forward