Joshua 1:8 is God instructing His children to meditate on His word, observe and do it and to do that day and night. The Holy Spirit helps us to observe and do the Word. We know from John 1 that the Word was made into human flesh and we know this person as Jesus Christ.
So when we observe the Word and when we do the Word, we are actually observing Jesus and doing like He did and still does. Philippians 2:5-8 encourages us to have the same mind as Christ: a mind ruled by love for God and led by the control of the Holy Spirit.
When we meditate day and night, it has to translate to observing and doing day and night. This daily action cannot be divorced from observe and do. All three go together.
Think of it this way: there is a promise at the end of observing and doing daily. So, each day brings us closer to the promise. Can we then afford to lose days and in so doing lose progress or delay the promise?
Observing and doing daily gets us to the blessing in the shortest possible time. Let the Holy Spirit help you in this process. My strong belief is that by doing that nothing will be unachievable in your lives.
Be blessed.
That Christian Next Door 