How do I resolve this conflict of interest?

TLDR: I want to go out for exercise/health. But I also need an immediate goal. So when I go out, I will always end up buying some junk food.

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It's such a nice day today. Let's go for a walk, get out the house and some exercise because I also love deals.

Hmm… where should I go? (Need a motivation)

I know let's go shopping! (Only reason to leave the house)

Takes a walk to Duane Reade (supermarket) 10 mins away.

It’s so hot/I want a reward!  I'm out already why not get a treat… let's see I can get a large Iced Coffee for $1 (or some other deal) at McDonalds (which is pretty much next door now that I'm here).

I mean isn't that a great deal! I could make coffee myself but only the KCup and well they wouldn't be cold. I want it cold now, not in an hour… (i probably won't when want it then). So that dollar is just for the coldness mostly and i guess the service cost.

Also since I'm here already, i save the food delivery fees (this also applies whenever I order for pickup: I save so much on the delivery costs and I get exercise too!)

Healthwise and financially, this negates any benefit of going out and probably would've been better had I not gone out and just ate the plain salad at home.