1 - My son, forget not my law; but let thine heart keep my commandments:
2 - For length of days, and long life, and peace, shall they add to thee.
This is the answer to father God's promise for things going well to and with us. He says “my son forget not my law" God is saying don’t forget his word, keep it and live it. “Let thine heart keep mine commandments” God knows your mind will be full of the things and lusts of this world and your flesh is going to have an appetite to do other things. God is saying keep my commandments out of your heart because in our hearts we all want to obey God, but our appetites get in the way and our soul’s lusts for things of this world and problems and concerns get in the way. God is saying keep my commandments and let them be kept by your heart/ Spirit man regardless. We’re not supposed to let our hearts be kept back or slowed down by our fleshly appetites or our soul’s desires, lusts, concerns, or problems.
Then He makes a promise in verse 2, he says “for length of days” meaning I’m going to add long and many days to you. He says long life, not living long he covers this with length of days, meaning you’ll live your many days in life; not fear, poverty, doubt, pain, death, fear, worry, or struggle. God is referencing the things that pertain to the essence of life in this scripture before he makes another promise; “and peace” (nothing broken or missing) all the things that are missing and broken will be restored, on you, with you, for you, through you, and after you. You’ll have abundance of them because nothing will be missing or broken. And "shall they add to thee", shall implies inevitability which means if you do these things they shall add prosperity and constant increase to your life. The sum of this is that your end will be far greater and more prosperous that your beginning ever was. Thy requirement is clear from God, don’t forget my words, my law but let thine heart keep them. God makes a great promise, but this scripture is also the answer to why Christians struggle; it’s because we don’t keep God’s word from our heart. We let one raindrop stop us from going to church we let one degree below 33 keep us from going to church, or from loving serving, obeying him, and keeping his commandments, we let so many things stop us. But God has promised through this scripture my sisters and brothers, that if we do these things long days, long life, and peace shall they add to thee.
So, it’s your responsibility, add them to you by keeping his commandments.