Difference between volitional +と思う and volitional+ と思っている?

Question

I've looked around the site for anything related but i couldn't find any clues. My take at it is that using the volitional form with と思う you're expressing your plans in the near future as in >今晩は薬を飲んで早く寝ようと思います。 you think you'll take your medicine then fall asleep probably said on the same day or even a few hours before doing the action. whereas volitional form + と思っている you're expressing your plans probably a few years in the future >来年、フルマラソンに挑戦しようと思っている。 you're thinking about taking on the challenge of a full marathon next year and probably saying that you've been thinking of taking on the challenge is correct too because you're still thinking, probably haven't even started preparing for it or probably even still considering it? I'm not really sure about this, it's just a speculation, is part of what i said correct?

Answer 1

Volitional + と思う indicates that you decided to do a certain action in the fairly recent past or at the moment of speaking, so the period of your thinking about doing this certain activity is short. On the other hand, volitional + と思っている indicates that you have been thinking about doing this certain action for a while (longer than just a short period of time) and you decided to do it a while ago. The difference between volitional + と思う and と思っている by itself doesn't tell us whether the action will be taken in the near future or the distant future; it simply signals that the length of time of your thinking is different.