The three main meanings of this verb are:
(1) 'become' Ћн стђл врачћм. He became a doctor.
(2) 'start' Ћн стђл читђть. He started to read.
(3) 'go stand' Ћн стђл у окнђ. He went and stood by the window.
When negated, this verb can be used as a kind of auxiliary verb, with the meaning 'won't, won't bother to, won't take the trouble to', as in the above conversation. Here is an example in the past tense:
(4) 'decide not to' Ћн не стђл спћрить. He didn't [bother to] argue.