Sometimes it's easy to feel overwhelmed or that you've bitten off more than you can chew. The truth is, you may have and you may need to ask God for wisdom about what you need to put down. However, if you find yourself in a position that you know God has set you in, but that you feel is just too big for you, then your solution is to look to Him and not yourself.
For I can do everything through Christ, who gives me strength. (Philippians 4:13, NLT)
Your strength comes from Jesus. He is the best everything. Look to Him and rely on Him to give you the ability you need to complete the task at hand. You were never meant to do it alone in the first place.
God is faithful and He never gives us more than we can bear. If He has given you more responsibilities, then trust Him to give you the strength, tools and resources you need to fulfil them.