Verified by 
A daily schedule can be a useful tool to help you enact particular habits every day. For example, perhaps you need to study for an exam on top of your work day, or you're training for a marathon. In my case, the daily schedule I've been sticking to for the last few months is pumping milk for my baby eight times a day (11, 2, 5, 8, AM and PM). I'm going to use that as an example a few times in this post. I apologize if that's TMI, but it's important to normalize this. These tips apply to any type of daily schedule.
1. Start with anchor habits
An anchor habit is something you do at a particular time of day that you're not at risk of skipping. It will help shape and structure your day. For me, my current anchor habit is my lunchtime. No matter what, I stop for an hour for lunch at 3 pm. This helps prevent me from drifting away and staying on schedule, it provides a hard backstop. I protect that time from any appointments, visitors, phone calls, and other concerns. If I get behind on my schedule, I know I need to get caught up by that time.
If you're consistent with an anchor habit, other people will get to know your schedule and know you're not available at that time.
It doesn't matter what your anchor habit is, but it should already be invulnerable to disruption for you. Another example might be the time you put your child to bed or bathe them, or drop them at school. If you're already very consistent with those times they'll work as anchor habits.
Don't choose something like a workout as an anchor habit if you struggle to get that done. To reiterate and summarize, pick an invulnerable habit.
2. Be very consistent for about three months
A schedule is a sequence of habits and habits get easier after a few months. With consistency and time, they become more automatic and take less willpower to maintain. Be very consistent with how, when, and where you perform daily behaviors until they reach this point. Behaviors only become automatic if you keep how and where you do them consistent, and they only start to require less willpower if they become more automatic.
3. Find a community
Join a community in which the schedule and or behaviors you're trying to maintain are normal. I like Reddit for this because it has lots of very niche communities, but some people use Facebook or other platforms. If you'd like to, interact in that community each day to help support you. For example, if you're training for a marathon, then you might join a community of people doing the same. When I was training in clinical psychology, my classmates were a natural community.
It's much harder to keep up any behavior or schedule if it isn't the norm for the people around you.
Even just checking particular Instagram or Twitter accounts each day can help support a journey if active participation isn't for you. Curate lists of people to follow.
4. Plan your rewards
Plan rewards and link them to the schedule you're trying to keep up in natural ways. Some of the times I pump, I'm able to watch YouTube or scroll on my phone when I'm doing it. Each time I pump is 30 minutes. If there's a YouTube video I want to watch that's about 17 minutes, then I know that over half the time I'm pumping, I'll have an enjoyable distraction. When a new video from a channel I subscribe to is released, I save watching it until I pump the next time. I don't feel the need to watch in between pumps, because I get plenty of time to do it during this.
Walks are another reward I enjoy. Because I like to walk in the sunniest part of the day, during winter that means the mornings. Again, this is another anchor-reward you can use.
Get to know yourself and what works for you. What do you want to do as a reward either during or after the daily behavior you're trying to maintain?
Tip: Whatever you like to daydream about doing can serve as a reward. For example, my rewards often involve researching travel (searching for the cheapest place I could fly tomorrow) even if that isn't an immediate possibility for me currently.
5. Use tools to support you, but not as your core strategy
Tools can help you maintain a schedule, but they don't magically do the work for you. For example, you might buy blackout curtains to help get your children to go to sleep on time in summer. Kitchen equipment might help support a cooking schedule, hiking equipment might help support an outdoor activity schedule, and so on.
It can be useful to think of buying tools as rewards.
6. Do only what's really important to you
Life is too short to maintain a daily schedule that's not incredibly valuable to you. It's okay if you're motivated by avoiding a negative, such as if you're motivated to study to avoid failing an exam. You may not want to maintain a daily schedule your whole life. In fact, there's a lot of value to changing up your routines as well, like that doing so boosts creativity. However, there might be periods in which a strict schedule is the only way you can get done whatever it is you need to do. In these scenarios, knowing how to successfully maintain a schedule is valuable.1
7. Try this thinking
Try to maintain an "I get to__" rather than an "I have to__." attitude. For example, I think, "I get to pump. I'm lucky I have a good milk supply. I have good nutrition and electrolytes, and the support of my spouse is available to help me do it. I'm lucky to have those things."
You don't have to be a Pollyanna all the time, but switch into this thinking some of the time when you know you need it. This isn't about virtue, it's about utility. Thinking "I get to__" will help you maintain the consistency you seek.
References
See the book Stress-Free Productivity.
