I must admit that I too suffer from the same plight! Tiredness is the soil by which sin germinate in my life it seems. It can be frustrating to feel helpless in the midst when we want to live godly lives. But I think it's important to realize that even on our best days, we're still heinously sinful! Remember the Greatest Commandment: "Love the Lord your God with all your heart and with all your soul and with all your mind." Not for one second in my entire life have I ever kept that command, the Greatest Commandment! Greater than thou shalt not murder! Greater than thou shalt not commit adultery! The more we understand the depth of our sin, the more hopeless it can feel to try and be better. Luckily for us, we stand before God washed of all sin and with a perfect righteousness, the righteousness of Christ. Next time you fall into sin while tired, let it be a reminder of your creaturely inability to even begin to be presentable to God, not in self-condemnation, but in order to magnify your dependence and thankfulness to Christ Jesus, our Lord and Savior! In these bodies, corrupted by sin, we grow tired, hungry, and sick, but God has made a way for us, in spite of our sinful flesh, to be made perfect in his sight so that we might enjoy the fruits of knowing Him and being adopted as His sons and daughters. We cannot even begin to clean ourselves up, but we can turn to God in the midst of our sin and praise Him for his glorious grace that He will remember our sins no more.

Francis of Assisi once said, “Preach the gospel at all times and if necessary, use words.” However, I'd say that words are almost always necessary. Jesus both acted and spoke in tandem in his ministry. Today's culture's version of 'niceness' often looks very similar to a Christian conception of neighborly love, so you don't want your actions to be misunderstood. The confidence with which you profess Christ as Lord will definitely turn heads more than acts of love would (although they should always go hand-in-hand).

You're right that we're constantly presented with so many worldviews on a daily basis. Luckily for us, God has given us the Holy Scriptures that we might know Him and his will for us. "All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work" (2 Timothy 3:16-17). Here we learn that the Bible is breathed out by God and sufficient for all that the Christian may face. "For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart" (Hebrews 4:12). We also see that God's word is more than mere words on a page, but an active force in the life of the believer. God speaks in what He has already spoken, so the Believer never has to feel as if they're without guidance.