One of Satan's favorite lies that he loves to whisper in a believer's ear is, "You're a failure." He'll tell you that you've always failed before so, of course, you're going to fail again, you're bound to fail. But, the very fact that you're hearing these lies indicates that Satan is aware that you are fully capable of reaching your goal. He certainly doesn't want you to reach it, which is why he's trying so hard to stop you.
If you believe your goals are God's will, nothing can stop you. You have the authority by the Holy Spirit to send the angels ahead of you to clear the way. Just ask God to release His angels. You can claim this verse:
Isaiah 45:2, "I will go before you and make the crooked places straight: I will break in pieces the gates of brass, and cut in sunder the bars of iron."
The devil's line of attack is designed to discourage and weaken you, to wear you down, and wear you out so that you won't have any courage left. Just remember next time you feel like life is too hard, that thought is not coming from the Lord. You're getting messages from the wrong broadcasting station. So, change channels right away.
God doesn't want you to be downhearted, doubtful, confused, or worried, much less depressed and defeated. Whenever these feelings begin to take over, it's a signal for you to rise up and fight. Don't just sit there, wallowing in self-pity, being tormented by the enemy! Shake it off!