I've played sims 4 for a while, I've noticed that there are two main factors that affect how a sim will/won't act/react to certain things: traits and emotions. For example, mean and evil sim will do mean interaction towards other sims. One time I met Malcolm Landgraab at nightclub, he talked to my sim with rude introduction. As for your sim who kept go jogging on his own, it was a highly chance that he had the active trait. Active sims love exercising, they'll get energized from time to time. And they'll get tense if they haven't worked out for a while. In your case, I guessed you didn't own any other work-out objects such as weight machine, treadmill, punching bag, basketball or climbing wall...ect, for your active sim to fill his needs of working-out. So the only option for your sim to exercise is jogging.
Remember trait is designed to equip a sim with some unique features or behavior. Usually, a sim tend to do something that is related to his/her traits when you're not assign him/her to do something. So if you don't assign your active sim to do anything, why not do something that he/she loves like exercising?
Another thing I want to point out is that: have you ever met any lazy sims in the gym? As far as I could remember, I've never seen game spawn any lazy sims, including pre-made ones, to exercise in gym because they hated sports. And if you do see a lazy sim exercise in gym, it's a hint that there aren't that many sims in your world, the game had no choice but pick a lazy one to be there. I noticed this before buying other packs which had more pre-made sims for the game to "use". I got the base game when it was free. I disabled the fill empty house to make it stop generating sims. With MCCC, my game-playing was fine until I got annoyed by a lesbian couple who kept showing up in the gym, even when I just used MCCC to make them go away! Remind you guys of that they were game-created townies, I just made them as couple and moved them in. But once I deleted them, Bob showed up in the gym! I was surprised to see him because I rarely met him. After I got other packs, he never showed up because the game had better options like Marcus Flex or Paolo Rocca, who had the active trait to play the role. Then it hit me the game was also aware of sims' traits. Anyway, my point is that trait affects a sim so much that it isn't just about a sim himself/herself, it'll also have some effect on how the game will go.
Based on my observation, the most powerful factor that can affect a sim's behavior is his/her current emotion. You guys know that certain emotion can help build a skill faster, or make a better performance. When a sim is in a specific mood, he or she will do the things that current mood will help. For example: when focused, sim will play chess, use observatory or microscope. When inspired, sim will play an instrument, go painting, or mix drink. Now knowing how emotion can affect a sim, you can "manipulate" NPC sims to do/not do things as you want. For instance, if you want a NPC male to ask your female sim out, all you have to do is make him flirty! The easiest way to do so is place a flirty painting when they're alone. When they're talking, try using non-romance interaction with him until he do romance with your female sim during the conversation. Once you get it and leave, you'll receive his phone call, asking you if you want to go out as a date with him.
I discovered this when my sim met Jade Rosa in the club. She got flirty from the DJ performance when chatting with my sim, then I saw the "chat with Jade" queue appeared a little one saying "be complimented appearance". My sims just reacted in a normal way, and there wasn't any romance bar between my sim and her. So I just ignored it until I got the phone call from her, saying something like she couldn't stop thinking about my sim, or couldn't get my sim out of her mind. I forgot what exactly she said but you guys get my point. This was a strong example how a sim can be affected by emotion. They'll try to romance with anyone when flirty.
To sum up, traits and emotions both play an important role in this game, be aware of this then you can figure out how to play this game properly by taking advantage of those traits and emotions.
