Actually talking about strength training (which he disses), no matter what sure got benefit here and there.
Road bike just came, no bike fit..... 4 rides over Sat and Sun today totalling 130km++, mix of whack, sprint, off saddle but majority Z2 grind.
No back pain no nothing despite no fitting. But back i can more or less feel a wee wee bit of strain (but not pain) coz of the more stretched out position . Even tried some km of psuedo TT position / puppy paws but i mindful of safety only tried on ultra familiar roads coz still getting used to it.
But of coz, nothing out of the ordinary, correct bike size, 170mm cranks (I'd prefer 165mm like on my foldie but that's for future change i guess. Dialed in (more or less) correct saddle height only solely based on inseam and height of fibula then use calculator. Front of patellar no issue no pain.
The rides, even if just using calculators and then confirmed via feel on rides, more or less feels ok.....coz i scared not tuned in then long term usage i spoil something kena injured coz of training mistakes (inevitable sometimes).
For those not been training for strength or similar isometrics like planks etc, my belief and what i have seen on youtube, for sure pecah....pain here pain there. I believe most useful for training is push ups, planks, any back exercises like pull ups, core stability stuff.
Now need to go find 3D printed saddle or a softer one. Butt pain.

This one bo bian......taobao way hope can find a cheap decent one that is good enough for 2.5-3hrs max can liao.
At first i was really really concerned and wanted to go for a pre-fit, even a basic cheap one to get the basics nailed down might be good. (that is the general recommendation). But, issue - a good pre and post fit costs like half the price of the bike.

It does not make financial sense.
But looks like what i suspected probably is correct. If you are conditioned, no issue one, unless if the bike is totally off (eg you go buy a L size 56 bike but you are 168cm tall, that one is cockster liao)
And then you go jump heckloads up in mileage coz new bike new toilet mah.......recipe for disaster.
If lagi jialat, injured some tendons here and there joined group ride and kena peer pressure / extreme training mistake , chao chao 2-3 months rehab one.
edit - of coz, just sharing what i have gone through and not trying to haolian....coz i have been long suspecting this. In fact, coz of T100, neck (upwards) strength i was even training for that for a few months. Aka like F1 driver like that.
Eg if one cant even do 20 push ups, cant plank 3 mins or 1 pull up or standing up on 1 leg also got issue liao, really need to go proper fitting...that one is almost confirm case need to optimize fit one else sure pain and cannot continue riding in such a higher-end hobby way.