Why do I have a strength penalty in Elder Scrolls: Morrowind?

In Elder Scrolls: Morrowind, I should have a strength of 40, but my character only has a strength of 25, and it is in red. I can't figure out why. It doesn't say that there are any ill effects on me, I'm not encumbered, and I'm using light armor, which I am proficient with. This is my first time playing. Please only respond if you have played the game and have a knowledgeable answer.Why do I have a strength penalty in Elder Scrolls: Morrowind?
You could be wearing a negatively enchanted item. (example it boosts your magicka but drains strength, which is pretty common on mage robes)Why do I have a strength penalty in Elder Scrolls: Morrowind?
Most likely, you were hit by a Greater Bonewalker. They are quite annoying because the spell they hit you with drains your strength. But unlike other spells, where the effect goes away once you kill the caster, this effect does NOT go away until manually removed.

Go to an Imperial Fort and find an alter to pray at. For the quickest access, fast travel via the mages guild to the Sadrith Mora guild hall. Exit the mages guild and go down the steps...I believe 1 flight of stairs...you'll find 2 doors. One for the fighters guild and one for the imperial chapel. Go in the chapel, pray at the alter (I think it's 25 gold), and select the option to restore attributes. This will remove the negative effects.

Edit:
Since this is your first time running through the game, I would highly recommend referencing the UESP for any help you may need with quests, items, etc. The site was put together by Elder Scrolls players for Elder Scrolls players, and is the most complete and avid community hub for the series.
http://www.uesp.net/wiki/Morrowind:Morro鈥?/a>