Rom 8:28-30  "And we know that for those who love God all things work together for good, for those who are called according to his purpose. For those whom he foreknew he also predestined to be conformed to the image of his Son, in order that he might be the firstborn among many brothers. And those whom he predestined he also called, and those whom he called he also justified, and those whom he justified he also glorified."

 The twin truths that are; 1. God is the one working in us to see salvation through to glorification-sanctification; and, 2. We must struggle with all our might to be obedient through faith and purify our hearts amid that struggle. 
Knowing that it is all of grace and that God will see us through it is the very believe that enables our hearts to not faint or fold. 

If He is for us no one or no thing can be against us. He is Absolute Love. Nothing can separate us from Him and His love. 

Rom 8:31-36  What then shall we say to these things? If God is for us, who can be against us?  He who did not spare his own Son but gave him up for us all, how will he not also with him graciously give us all things?  Who shall bring any charge against God's elect? It is God who justifies. Who is to condemn? Christ Jesus is the one who died--more than that, who was raised--who is at the right hand of God, who indeed is interceding for us.  Who shall separate us from the love of Christ? Shall tribulation, or distress, or persecution, or famine, or nakedness, or danger, or sword?  As it is written, "For your sake we are being killed all the day long; we are regarded as sheep to be slaughtered." 

Through His love we conquer and over come all obstacles. 

Rom 8:37-39  "No, in all these things we are more than conquerors through him who loved us. For I am sure that neither death nor life, nor angels nor rulers, nor things present nor things to come, nor powers,  nor height nor depth, nor anything else in all creation, will be able to separate us from the love of God in Christ Jesus our Lord." 

I highly recommend the book "FUTURE GRACE" by John Piper below is an excerpt.
"What emerges... is that faith is the God appointed means of justification and sanctification because, better than any other act, it highlights the freedom of grace and magnifies the glory of God. It does this because, at its heart, faith in future grace means being satisfied with all that God promises to be for us in Jesus. This kind of faith magnifies God because God is most glorified in us when we are most satisfied in him. 
... faith and love are are the conditions a Christian meets in order to go on enjoying the benefits of future grace. But faith and love are not conditions in the same way. Faith perceives the glory of God in the promises of future grace, and embraces all that God promises to be for us in Jesus. This spiritual apprehension and delight in God is the self-authenticating evidence that God has called us to be beneficiaries of His grace. This evidence frees us to bank on the promises as our own. And this banking on the promises empowers us to love others, which in turn confirms our faith is real. Thus faith is the bottom line condition that unites us to the power of future grace; and love is a condition only in confirming the reality of this faith."  Piper, John,  The Purifying Power of Living by Faith in FUTURE GRACE ,Multnomah Books, Sisters, Oregon. 1995 p. 19


2Co 5:14-17  "For the love of Christ controls us, because we have concluded this: that one has died for all, therefore all have died; and he died for all, that those who live might no longer live for themselves but for him who for their sake died and was raised.  From now on, therefore, we regard no one according to the flesh. Even though we once regarded Christ according to the flesh, we regard him thus no longer.  Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come."