So I've been telling myself I want to gain weight/strength for a few years now, but pretty much never change. This is mostly due to lack of a caloric surplus as I have no trouble with working out.

Actually, I tend to get extremely anxious if I don't do something every day. I know all of the rest to grow principles and fact that trying to chase 2 different goals (endurance/conditioning and building muscle) is very difficult, but I simply don't put them to practice.

I'm 5'10, 155lbs and 31 y/o. I'm familiar with the compound lifts and not a newb in that regard, but looking for any stories from others that have dealt with this. I used to run marathons and don't care for that anymore, but find myself trying to do some form of cardio every day!

Also, looking for a good routine to stick with so I have something in my face and will follow. I've done 5/3/1 and like it, but any other suggestions. Thinking upper/lower split would be best for me, but again, looking for thoughts from you guys that have passed this mark.