Exercise is a very high hurdle for people. Even harder if they don't have a successful history with it (like me).
I didn't get unstuck on this until a few years ago when there was a research paper that refuted the 20 minutes of uninterrupted cardio advice. I know too many people who feel like they're gonna die around the 14 minute mark, and they just give up.
Turns out that 3 intervals of 7 minutes is enough to show progress. You can duck out of work for 8 minutes in the afternoon and take a walk without even getting sweaty. Do it again at lunch and after work and you've got your 20.
Doing 14 minutes is still better than 0 minutes. The difference between 0 and 10 minutes is likely higher than the difference between 10 and 20 minutes.
Start easy. Don't put the goal too high. Don't have a defeatist or perfectionist attitude (relapse is a natural part of changing a habit). If you have to stop earlier because your body tells you so, accept that, and retry the next day. Once you start doing it regularly you'll notice the difference. It will go easier. Especially in the start. Later on, you can increase your limit, aiming higher, until you meet your goal.
If you're doing it regularly and then end up skipping it once, the effect of that is negligible (unless you're pushing it but you're not an athlete, are you?). Just like if you're eating usually healthy and not too much the impact of that Christmas dinner is minimal. Just like with brushing your teeth if you brush them twice a day and end up skipping it once, it isn't a big deal but if you regularly skip and neglect your teeth there will be more of an impact.
Realizing that makes say losing weight, getting fit, and maintaining dental hygiene easier. Heck, it makes life in general easier as well since it is never too late to start compared to going on with the bad habit. I loved your GP comment as well, it makes so much sense, and has a similar soothing effect. Thank you for making that point.
Doing 14 minutes when you aren't in your optimal energy zone can be worse than zero. When you are fatigued, you create more work by being sloppy or in general doing things which require more work down the line (especially for programmers).
I go to a gym once a week. When I started 5 years ago, I was spending like 20 minutes doing high-intensity strength training. It was enough to make a steady progress and build muscles albeit slowly. After 4 years I hit a plateau. So now I spend like 50 minutes in a gym still once a week to continue the process.
I doubt that I can stick to anything that requires more frequent efforts. 15 years ago I begun to train karate, but training twice a week for 2 hours was too much so I eventually dropped out.
Maybe try different things. Some people "don't like exercise" because they don't enjoy the gym or running. But put them on a dancefloor / skateboard / ocean beach / roller-rink / climbing wall / mountain bike / zipline / parkour course / yoga studio .... etc, and it clicks. If your form of exercise requires "willpower" to do it, that's probably not a good indicator for long-term engagement. Personally, I hate gyms but I'd go surfing even if it made me fat.
I didn't get unstuck on this until a few years ago when there was a research paper that refuted the 20 minutes of uninterrupted cardio advice. I know too many people who feel like they're gonna die around the 14 minute mark, and they just give up.
Turns out that 3 intervals of 7 minutes is enough to show progress. You can duck out of work for 8 minutes in the afternoon and take a walk without even getting sweaty. Do it again at lunch and after work and you've got your 20.