Mindfulness.
I started with just sitting down a pillow, knees confortably below my hips, eyes closed, breathing in through the nose, out through the mouth (though I just used my nose after a while).
Focused on the feeling of my chest calmly moving as I breathed. Every thought that crossed my mind was allowed, however I would not be allowed to develop it. I would just refocus on my breathing.

Some sessions would be only thoughts, some would be alright. Didn't matter, I just had to do it every day. I even started a decoy meditation habit at one point when I was overly stressed : I would start meditating for 30s, then stop, write down every "important" thought I just had to empty my head, and then start the real meditation.

Scheduling conflicts since I was doing it before sleeping, even though I used to do it no matter where I was. It helped me tremendously with a depression I was battling at the time.
Easy to do when I was single, got more lenient when I was not. Missed a session here and there, it obliterated the habit.

Stopped meditating recently after doing it everyday for 5 years. Anxiety has been slowly creeping back, and my sleep is getting utterly fucked.
I'm pretty sure meditation is the key to 90% of my mental problems at the moment, but one of them is task paralysis, which also includes meditating... Damn that brain...

Edit : people interested should definitely check out the vipassana method of mindfulness meditation. They also offer free 10-day meditation courses, but that's quite extreme, though immensely valuable.