Im gonna retract this one. Recommends some suboptimally dangerous stuff. Also gives people the wrong idea. I have at least tried anything I recced. But I don't personally use all these things. I only ever recommended them to solve problems you actually had. But given how crazy things have gotten in the rat/ea community I no longer really recommend people explore crazy stuff.
To stay with the drug theme: I've had moderate success using nicotine lozenges to "jumpstart" an exercise habit. For the uninitiated, nicotine is habit-building more than it is directly addictive and slow-release forms like lozenges or patches are relatively safe. I had no trouble stopping the lozenges after a few weeks and the habit stuck.
Do be careful with this if you have any cardiovascular ailments (particularly hypertension), as nicotine is a vasoconstrictor.
IME there is a real effect where nicotine acts as a gateway drug to tobacco or vaping
in general this whole post seems to make this mistake of saying 'a common second order effect of this thing is doing it in a way that will get you addicted - so don't do that' which is just such an obvious failure mode that to call it a chesterton fence is generous