JOEL - Here is the scripture you referred to:

"And moreover, I would desire that ye should consider on the blessed and happy state of those that keep the commandments of God. For behold, they are blessed in all things, both temporal and spiritual; and if they hold out faithful to the end they are received into heaven, that thereby they may dwell with God in a state of never-ending happiness. O remember, remember that these things are true; for the Lord God hath spoken it." (Mosiah 2:41)

One aspect with this scripture has to do with the fact that the commandments themselves are a blessing to us. They are guidelines to happy living. They protect us from all the serious pitfalls of life. They are the pathway to peace and joy. They help us know how we should live our lives, and are a strong rod that we can hold on to with confidence.

This scripture also goes along with the promise that God has made with us that if we do what He says we will be blessed. In fact there is an eternal law that requires Him to bless us if we do keep His commandments, as explained in the following scriptures:

I, the Lord, am bound when ye do what I say; but when ye do not what I say, ye have no promise. (D&C 82:10) There is a law, irrevocably decreed in heaven before the foundations of this world, upon which all blessings are predicated--
And when we obtain any blessing from God, it is by obedience to that law upon which it is predicated. (D&C 130:20-21)

In other words God is obligated to bless us in some way if we obey the law or commandment upon which that blessing is predicated. Of course the receipt of blessings is not the main reason we keep the commandments. It is only a consequence of keeping them. We keep the commandments because we love God and want to obey Him:

If ye love me, keep my commandments. (John 14:15)

For this is the love of God, that we keep his commandments: and his commandments are not grievous. (1 John 5:3)

Many of the blessings we receive are dependent on the wisdom and grace of God and what ever He determines the blessings should be. He knows us better than we know ourselves so we can not be presumptuous enough to try and tell God what we think those blessings should be. However, there are some commandments which do have related blessings attached.

If we keep the Word of Wisdom we are promised;
"all saints...shall receive health in their navel and marrow to their bones;
And shall find wisdom and great treasures of knowledge, even hidden treasures;
And shall run and not be weary, and shall walk and not faint.
And I, the Lord, give unto them a promise, that the destroying angel shall pass by them, as the children of Israel, and not slay them." (D&C 89:18-21)

If we pay our tithes and offerings:
"Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the LORD of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that [there shall] not [be room] enough [to receive it].
And I will rebuke the devourer for your sakes, and he shall not destroy the fruits of your ground; neither shall your vine cast her fruit before the time in the field, saith the LORD of hosts.
And all nations shall call you blessed: for ye shall be a delightsome land, saith the LORD of hosts." (Malachi 3:10-12)

"Behold, now it is called today until the coming of the Son of Man, and verily it is a day of sacrifice, and a day for the tithing of my people; for he that is tithed shall not be burned at his coming." (D&C 64:23)

If we keep the commandments God will help us better understand His doctrine:
"But unto him that keepeth my commandments I will give the mysteries of my kingdom, and the same shall be in him a well of living water, springing up unto everlasting life." (D&C 63:23)

Of course the main blessing we will receive for keeping His commandments is eternal life:
"And, if you keep my commandments and endure to the end you shall have eternal life, which gift is the greatest of all the gifts of God." (D&C 14:7)