I've learnt some "hacks" from How to ADHD (both the YouTube channel and the book).
Something that works for me is "bribing" myself. Either with a planner you enjoy filling, a calendar with stickers, or a reward like TV time or music (not food), give yourself a reason to do your activities beyond the activities themselves.
Another one that's not always possible for me, but works, is getting non-negative external pressure. Deadlines often get people to start, but that's too much stress, and we don't want that stress. A similar thing to a deadline without the anxiety is body doubling. It consists of doing your activity while other person or people do theirs, and you can report back in the middle or only at the end. The idea is that you feel like you need to do it because people are counting on it, without it being super stressful. You might feel watched, you might feel their expectatives on you, you might simply want to exchange your results at the end. However it goes, it might work for you. A variant of this is telling your plans to someone important and then you'll feel like you need to do it so you can tell them how it went.
My emergency remedy (only when I'm unmedicated for ADHD, because I wouldn't mix it with my medication): caffeine. Caffeine is a stimulant, so it has interesting effects on people with ADHD. Depending on age, metabolism, and quantity, it can be relaxing or "quieting"; it can also help with focus; and it can give a boost to productivity. A cup of good coffee and I do the laundry, cook, write back to people, etc. Now, be careful because a) you can become hooked to caffeine and become one of those people that cannot function without it, b) even without an addiction, if you use it too much, your body will get resistant for a time and it will lose its effectivity, c) some cannot tolerate caffeine well, for example, people with cardiopathies or bipolar disorder. I cannot drink it for long without causing havoc in my sleep and mood. Be careful with caffeine.
And those are the strongest for me. I do recommend getting the How to ADHD book, even if you're not dealing with ADHD but a mood disorder, a difficult time in your life, etc. The tips are helpful nonetheless.