What am I supposed to do on Sunday, just sit around and read my scriptures and pray all day Sunday?

Spencer W Kimball, Miracle of Forgiveness, 96–97

“The Sabbath is a holy day in which to do worthy and holy things. Abstinence from work and recreation is important but insufficient. The Sabbath calls for constructive thoughts and acts, and if one merely lounges about doing nothing on the Sabbath, he is breaking it. To observe it, one will be on his knees in prayer, preparing lessons, studying the gospel, meditating, visiting the ill and distressed, sleeping, reading wholesome material, and attending all the meetings of that day to which he is expected. To fail to do these proper things is a transgression”

Isaiah 58:13-14

13 ¶ If thou turn away thy foot from the sabbath, from doing thy pleasure on my holy day; and call the sabbath a delight, the holy of the Lord, honourable; and shalt honour him, not doing thine own ways, nor finding thine own pleasure, nor speaking thine own words:

14 Then shalt thou delight thyself in the Lord; and I will cause thee to ride upon the high places of the earth, and feed thee with the heritage of Jacob thy father: for the mouth of the Lord hath spoken it.

Do Good

Luke 6:8-10

 8 But he knew their thoughts, and said to the man which had the withered hand, Rise up, and stand forth in the midst. And he arose and stood forth.

 9 Then said Jesus unto them, I will ask you one thing; Is it lawful on the sabbath days to do good, or to do evil? to save life, or to destroy it?

Take Inventory

“The Sabbath is a day on which to take inventory—to analyze our weaknesses, to confess our sins to our associates and our Lord. It is a day on which to fast. … It is a day on which to read good books, a day to contemplate and ponder, a day to study lessons for priesthood and auxiliary organizations, a day to study the scriptures and to prepare sermons, a day to nap and rest and relax, a day to visit the sick, a day to preach the gospel, a day to proselyte, a day to visit quietly with the family … , a day for proper courting, a day to do good, a day to drink at the fountain of knowledge and of instruction, a day to seek forgiveness of our sins, a day for the enrichment of our spirit and our soul, a day to restore us to our spiritual stature, a day to partake of the emblems of [Jesus’] sacrifice and atonement, a day to contemplate the glories of the gospel and of the eternal realms, a day to climb high on the upward path toward our Heavenly Father” (The Teachings of Spencer W. Kimball, ed. Edward L. Kimball [1982], 216).'

Pray

Doctrine and Covenants 59:9–10, 13
9 And that thou mayest more fully keep thyself unspotted from the world, thou shalt go to the house of prayer and offer up thy sacraments upon my holy day;
10 For verily this is a day appointed unto you to rest from your labors, and to pay thy devotions unto the Most High;
13 And on this day thou shalt do none other thing, only let thy food be prepared with singleness of heart that thy fasting may be perfect, or, in other words, that thy joy may be full.

The above scripture goes toward answering the question, “What am I supposed to do on Sunday, just sit around and read my scriptures and pray all day?”

Elder L. Tom Perry, The Sabbath and the Sacrament

“Let us prepare and conduct ourselves on the Sabbath in a manner that will call down the blessings promised us upon ourselves and our families. “