Motivation for Mass gaining!!

I'm in the same boat. I've hit my weight loss goal, and I'm now focusing more on adding muscle.
I've found that slow and steady is the way to go, though as a fellow impatient person it's hard!!
Paying more attention to my macros has helped. I'm a carb fiend, so making sure that I'm not over doing it and upping my protein intake has been good. I'm also walking over my lunch break pretty much every day at work and going to the climbing gym 2 or 3 times a week.
I don't know about you, but just going to the gym and picking up heavy things and counting to 10 over and over just didn't work for me. I get bored and impatient. Finding climbing has been the key for me. I have specific, measurable goals, both short and long term, and it keeps my brain engaged. Plus I can be social with other climbers if I want or just have some focused solo time on the wall.
Even if climbing isn't your thing, finding that thing that will keep you interested and engaged is really important. Some people genuinely enjoy the pure weight lifting process and that's AWESOME for them, that's their "thing", but I think most of us need something else to keep interested.
It's so much easier to want to hit your food goals and your exercise goals if you're working towards something bigger than just " looking good".