God can do new and amazing things each day. In the beginning, God created light, heaven, and earth in one day (Gn 1:1-3). The next day He created the sky (Gn 1:8). The day after that He created plant life (Gn 1:12). Since God is the same today as He was when He created the earth (Heb 13:8), it follows that He is creating something new and exciting this very day.
When we come to know God as the Creator, this realization leads us to new hope. God's very nature is to create; thus, God creates new things each day, just as He did "in the beginning" (Gn 1:1). Each day God can make a new creation out of nothing, and can create good from bad (Rm 8:28). Each day is a new day God has created.
Therefore, if we've had one bad day (or many bad days), it doesn't mean tomorrow will also be bad. The author of the book of James tells us: "You have no idea what kind of life will be yours tomorrow" (Jas 4:14). We can never lose hope, because God's love and mercy come anew every morning (Lam 3:22-23).
This is why Jesus teaches us to pray only for the needs of this day (Mt 6:11), to not worry about tomorrow, and to deal with each day as it comes (Mt 6:33-34). Therefore, "today, if you should hear His voice, harden not your hearts" (Heb 3:7-8).
Never lose hope, for God can create a future full of hope for you on any given day (Jer 29:11). "This is the day the Lord has made; let us be glad and rejoice in it" (Ps 118:24).