Not just one reason, but I stopped because I more or less maintained my physique for 7-8 years afterwards (probably being in your 20s helps) and my life circumstances were in a goldilocks zone; my dad (a doctor) was adamant I'd destroy my heart with all the muscle mass I added.

The thing that motivated me to start was the fact I was not very successful with girls and gaining 30 pounds of muscles in early 2000's Romania was intoxicating, if anybody told me before that girls would send kisses in the subway, grab my arms in the bus and start conversations with me or ask for my number in clubs, colleagues ask me to dump my girlfriend I would have said it's impossible.

I'm ashamed to say, but all that validation was even better than the way lifting made me feel and the primary drive to weight lifting.

It's only now that I remember how good weight lifting in itself made me feel, I never did give it much thought back then.

But now it's very hard to find the time or motivation to start it again.

I'm not really scared of getting fat down the line, I'm in my early 40s now and I've never been fat.

You could be right, that it's only the change that makes you feel amazing, and I only ever went to the gym for some 6 months total, but I have my doubt that it would ever go away, I've been on many, many drugs, NOT ONE ever made me feel good for 6 months straight, they all downregulate very fast.

Now thinking about it, I get a renewed motivation to re-start weight lifting

And this is incredible motivation for me. I’m in my 40ies, and have been unsuccessful with girls. Of course being in your 20ies helped because that’s when good stories start, and at 40 women are already taken, but I find it a decent explanation of the times I was successful or not and it’s worth trying again. I was very fit at 30 but never muscular, just a guy with 8 hours or random sports per week, so like you before 18. I still do 3-5 hours of sports per week, I should redirect that towards gains.

> And this is incredible motivation for me.

Two caveats: I'm talking about early 2000's Romania where it was quite rare to see really muscular men AND I was in my early 20s, I have no clue if men in their 30s or 40s get the same kind of attention, it was the shallow kind of attention.

By the time my 30s hit I was already married, however we did have a very rough patch where we were very close to divorce, I traveled alone, was part of an NGO and I think a lot of the young women there got a strong clue about how rough things were between me and my wife because I also got a lot of attention from women back then but then it wasn't because of physique - it was because I was their photographer and high status in the NGO and much higher net worth.

Going the traveling groups, I also did get quite a bit of attention, because there were a lot of single women in their late 20's and I'm sure a lot of them got this fantasy they would find their soul mate on such a trip and I was 100% not interested in anything romantic but I was very open to socialize. All sorts of un-intended "adversarial" techniques I noticed worked -- again my portrait photography hobby seemed attractive to the ladies, when I noticed one was too interested, I pulled away so she won't get the wrong idea, which made her even more interested, I also chatted up foreign women in the hostels because I was geniuinely curious about their background -- I had a long conversation with a hot, early 30s phd in fish farming and a young woman in our group started interrupting us by saying "You know, we've been together in this group for 3 days and you haven't spoken to me as much as you did to this foreigner, why?". I clearly remember I talked to a psychology major woman in the bus because I'm very interested in psychology and I did quite a few years of psychotherapy and I'm very interested in Schema Therapy. At some point we discovered we run in the same park and she invited me to run together. It was then that it hit me she probably had the wrong idea, but I felt it would be weird to say "that's great but I'm married" and I was in a headspace where if I wanted to I would have gone with her for a run regardless of what my wife thought about it, but I also got the feeling this young woman will not take it well if I said I was married, so I just started avoiding her. I noticed she tried even harder to approach me. Later that evening one of of the women in the group asked me "Oh wow, so I checked your facebook and you're married?". And I said, "Yes." . That young woman just blurted it out "But I asked you to go running together, why aren't you wearing your wedding band????".

The point I'm trying to make is I'm sure having a great physique is sure to be helpful even in your 30s and 40s and it will certainly set you aside, but there are other, more powerful tools to build attraction, alas, some quite manipulative (like social proofing, oblique approach, status, feigned low interest, push pull, triangulation).

I think it's very important to understand where you stand, where your target demographic stands, and where your competition stands.

If you're in an area where all the guys are super fit millionaires, you're not going to have much luck with the ladies there.

I was never in the pickup scene, and I've seen some terribly messed in the head men because of it (bitter redpill types), but I think there are quite a bit of spoken or not so spoken psychoevolutionary tricks out there great to know and take with a huge grain of salt.

Probably the biggest trick is no trick, but to actually be ok with yourself, empathetic, reasonable, have fun by yourself, explore, have healthy boundaries, but still generous, not have/display emotional baggage, basically present yourself as being what the kind of woman you want also wants.

Strength Training also feels intoxicating for me. I am in my 20s.

I also feel the need to control this entity of excitement with the rest of my life, my studies, career and romance.