This is a very good question and I want to address it from several different approaches.
First have to go a little deeper into the reason you believe that you are here on this earth.
The bible has many examples of why God put us here. At the for front among those is to prove us or test us.
Judges 2:22, That through them I may prove Israel, whether they will keep the way of the Lord to walk therein, as their fathers did keep it, or not.
23, Therefore the Lord left those nations, without driving them out hastily; neither delivered he them into the hand of Joshua.
So here we see an instance where the Lord comes strait out and says I am testing you to see if you will follow the commandments. This is important to note because for something to be a test you necessarily have need the option to be able to fail. Which means that we have agency or the ability to choose for ourselves what we will do in life.
Since we have agency that means that there is opposition because you can't have choice without opposition. This is important to note because you say that you are learning that you have to accept whatever someone does to you because its God's will. That is not necessarily the case. The Lord
lets the rain fall on the just and unjust alike and He allows somethings to happen to good people because it needs to be that way if we are going to choose to follow Christ.
Jesus admonished the sinners that He healed to
go and sin no more. Why would He do this if everything that was happening was being caused by God? He said this because not everything that was happening was being caused by God but by people exercising their agency to choose the devil instead of God and hence sinning. So we can see that while everything is allowed by God not everything is caused by Him, a very crucial difference.
That lets us address the part of your question where you say that we need to lean on the Lord and not our own power. This is true. Because we all live in a fallen state no matter how much we want to we will at one time or another exercise our agency to choose to follow the devil and sin. To return to the path we need to lean on Christ and His Atonement for us. The scriptures say that there is no other way to return to live with God.
So we are being tested yes, we need to make our own decisions to live up to that test but when we fail we need to rely on the Lord to make that up because we can't do that ourselves.
Here is a scripture to go with the importance of doing works ourselves and yet rely on the Lord at the same time:
James 2:14-21) 14: What doth it profit, my brethren, though a man say he hath faith, and have not works? can faith save him?
15: If a brother or sister be naked, and destitute of daily food,
16: and one of you say unto them, Depart in peace, be ye warmed and
filled; notwithstanding ye give them not those things which are
needful to the body; what doth it profit?
17: Even so faith, if it hath not works, is dead, being alone.
18: Yea, a man may say, Thou hast faith, and I have works: shew me thy
faith without thy works, and I will shew thee my faith by my works.
19: Thou believest that there is one God; thou does well: the devils
also believe, and tremble.
20: But wilt thou know, O vain man, that faith without works is dead?
21: Was not Abraham our father justified by works, when he had offered
Isaac his son upon the altar?
Abraham did not know ahead of time that a substitute would be there to be offered instead of his son yet he proved himself worthy by relying on the Lord for that difficult trial and passed his test. Similarly we need to show our faith by our works which means that we need to get out and do service.
Feeling good about ones-self is paramount to the gospel and enshrined in the second commandment given by Christ:
Thou shalt love thy neighbor as thyself. (emphasis mine)
You can't love yourself if you don't feel good about yourself so while we should not feel boastful we should feel good about what we have accomplished serving the Lord because it shows our faith and that we are striving to pass the test given to us.
So to sum up: In order to prove ourselves we need to have agency which requires that we think for ourselves and choose to freely follow God. We need to do hard work to show our faith and pass our test. And we should feel good about what we accomplish because it shows that faith (and anything that involves building faith is including the Lord), and shows we are doing our best. And its commanded by the Lord. In all of this we must remember that we will slip up from time to time and it is at those points when we must rely on Christ to make up for our sins.