Challenge yourself is good for improvement, however everyone has a limited 24 hours per day. 5 concurrent objectives is considered enough.
An objective should be ambitious enough to make you feel slightly unconfortable, otherwise you don't need OKRs. It should be task if you feel easy to achieve in a short time.
Everyone loves number and loves money, but objective shouldn't be a metric-driven one. It needs to be inspirational, a call-to-action that get you to leap out of your bed, ready for a new day and a new challenge.
Different from Objective which should be ambitiuous, the Key Result must be able to measure the percentage of achievement. And you should constantly tracking at least bi-weekly for its progress.
A good Key Result is something that you can measure the progress a long the time, otherwise it's just an action that should have to do. For example: "Think about improvement for your day" is definitely not a key result. A better one is "Have 30 minutes per day for reading", after achieving it, you can add more results which prove that your day is more meaningful.
Tracking the progress is critical for getting forward of doing anything. It helps you know the current state and plan for actions to accomplish it. Be sure to review your key results regularly to track your progress, manage your pace and effort, and seek guidance for your next steps.
You miss 100% of the shots you don't take.
