It turns out that the speed of light (186,282 miles per second) is actually quite slow! In the vastness of space that speed is achingly tortoise-like. James O'Donoghue, a planetary scientist at NASA's Goddard Space Flight Center, shows us that light takes 3 minutes 2 seconds one way to travel between Earth and Mars. YouTube has the animated clip and watching it for three odd minutes is painstaking.
The point being that what may seem impossibly fast from our perspective, is not so fast in the grand scheme of things. How BIG are your problems? From your perspective, overwhelming? Unattainable? How about taking a step back in space, time and thus perspective? The view is a lot different.
When God says "don't be afraid", or "do not worry" He is not devaluing your challenge; what He is communicating is from HIS perspective - allow Him therefore "in" on your struggle. Philippians 4:6-7 says, "Don't worry about anything; instead, pray about everything. Tell God what you need, and thank Him for all He has done. Then you will experience God's peace, which exceeds anything we can understand. His peace will guard your hearts and minds as you live in Christ Jesus".
Did you see that? "...exceeds anything we can understand". Well, how fast is that? Faster than light for sure. It is the speed of His love that is so quick it travels inter-dimensionally, from Him to You.