"I love to walk."
Translation:Αγαπάω να περπατώ.
In general, it's true that the present subjunctive conveys the meaning of an action of longer duration, whereas the aorist subjunctive is mostly used to either talk about momentary actions or actions/decisions that shall happen and be concluded shortly. I get what you're saying in your example, but the thing is that the aorist subjunctive just doesn't work in the case of "to like/love+gerund/infinitive". Check out the difference:
"I like walking in the morning"=Μου αρέσει να περπατάω το πρωί. (Walking in general, yes, but there's no other option anyways, since it'd be wrong to use the aorist subj. here.
I want to walk=Θέλω να περπατήσω (I want to walk now, so I shall do it now, aorist subjunctive). Keep in mind, however, that there's no "I love/like to..." in this example.