Apart from illness, the pain you feel is brought about by your values, rather than something that truly exists. There is no need to stand at the age of 50 and regret the life of your 30s, nor to stand at the age of 30 and regret the love of your 17s. We cannot stand at a later height and criticize our past selves; that is unfair. If given a second chance, with the mindset and experiences of that time, we would still make the same choices. So learn to reconcile with yourself and accept every version of yourself at each stage.