In all honesty if I had the benefit of hindsight and being able to go back to a point of time in my life, ideally I'd pick it to be about 15-16 years of age. I lacked so much confidence at that point in time. No doubt I'd have asked out a few of the girls who showed interest back then. God knows how that might have worked out. But it's a series of regrets I sometimes have when I evaluate my life. I really didn't see much value in myself as a prospective romantic attachment until I hit my late 20's. To an extent, I look at what I'd like from my love life and think now that it's probably too late to get started with having kids at 40. I look at some of my nephew's and nieces and think that I could have offered a good upbringing to my own kids if I didn't let missed romantic opportunities through a lack of confidence, and later on ethics rule my decisions.
At that stage I was also a touch ashamed to stand up academically in areas where I could. School was always so easy to coast through. Without having ever studied, I always managed to be about the second best or third best student in my classes even if I hated the subject. When I hit University I joined a huge group of people that in some cases were less intelligent, but more focused and I coasted through that until I quit uni at 22 because I fell into a supervisors job that I felt would take me further sooner.
My supervisor job at that point I rage quit because I was being paid below my responsibility level. I got pretty pissed off that for three years I was paid about 30k a year when the salary I should have been earning was 50-55k. I got into the mindset that I wasn't taking on that responsibility again any time soon. I trained 5 of my future supervisors at work by the time I was 30 and part of that was because I always planned to get out of the industry I still work in 15 years later. It remains a part of my life that I coast through.
In summary, I think that I have this mentality that it's ok to not go far if I'm coasting, but I'd be very disappointed if I failed when I was trying my best. If I could go back to 15 or 16 armed with my knowledge of the regrets I'd have now, I'd have applied myself more romantically and academically from a young age.