니까 들다

a thought comes; or pick up

"-(으)니까" gives the trigger, and 들다 after it splits into two unrelated senses in these lines. In the idiom 생각이 들다 or 기분이 들다, a thought or feeling arises: talking about it is making me think that again, the mood I get when I sit down to write this. In the rest it is the physical verb — you've brought it with you, I don't think I could even lift it, let's pick it up and stand, he lifts it because you threw it. The verb before -니까 tells you which one you have.