I've found the best advice that Mark Rippetoe gives in his lifting books is to keep a journal. Without it I would not have been pushing myself always to add a little more weight with every session. I wouldn't necessarily realise that I was always able to add more. I would probably also not be bench pressing more than twice what I started with under two months ago. (It's still embarrassingly feeble. But yeah.)
I've found that the most bonkers advice from the same books is to just eat a regular diet - and then also drink an entire gallon of milk every day. I haven't followed this advice and I don't plan on it.
Still I've gained about 6 to 8 kg. I'm pretty sure most of it is muscle.
I'm not sure how all of this will affect my running, which I haven't given up. Things have definitely changed, though. My body probably hasn't changed so much so quickly since I was a teenager.
Now when I run almost everything feels different. Weight lands differently somehow with every step. There's also constant low-level soreness almost everywhere that has a muscle. I had expected that lifing would destroy my marathon times, and it still might - just because of all the weight gain.
But I'm not entirely sure, and here's why: Whenever I have a day of particularly intense squats, both my quadriceps are sore in the area about three to four inches above my knees.
This area has also been the first part of me to fail in every single marathon that I've ever run. I've always had plenty of stamina, my joints have all been fine, and my lungs and the rest of my muscles have been okay too. But that part right there somehow stops working properly, and I can't run much anymore.
I'm thinking squats might help that, and if so, it will go a long way toward improving my times. Lifting might be the best thing I've ever done for my running.