I run now and then, but want to run consistently, I’m thin and have a high metabolism, so I don’t gain weight too easily.

I want to build some lean muscle, not get jacked or anything, and I’m prepared to eating heathily… but I’m not a huge fan of the whole 45 min. long workout routine (only because my willpower seems to fade a few weeks in)

So how can I accomplish this while running every two days or so?

Which exercises will be most effective?