The key is not what app to use but breaking down the goals into small steps known as tasks. As small as possible. For example, say your sprinkler is broken and you need to fix it because your grass is starting to die. What do you put on your calendar?

Most would put “fix sprinkler.” But that’s not useful and it’s not a task. It’s more of a goal. If you can’t do it in one step, then it’s a goal that needs to be broken down into tasks. Tasks are single step actions that get you to completing a goal. A better thing to do is break down the goal into the simplest braindead steps possible (tasks). So your calendar should say “look for tutorial on how to replace a sprinkler” then “assess the problem.” Or if you’re not going to do it yourself, then you would put “look for a gardener to fix sprinkler” then “go to Home Depot and buy a sprinkler for the gardener.”

I use proton calendar but any calendar that you’re comfortable with should be fine