This mod makes Alex slightly shorter, gives him a younger physique and shorts instead of long trousers. I created the changes via editing the original sprite for Alex.

I made this mod because some of my favorite portrait mods make Alex and other villagers look considerably younger whilst not changing the character sprite. I'm not really an artist so I apologize if this isn't up to your standards. 
I've done Alex in particular because I personally find him annoying as a buff adult, I think his overly arrogant ambitious side is more endearing and less abrasive as a younger or smaller character because his ambition to be strong conflicts with his image, giving him a different reason to train and take his exercise seriously. 

Here are links to some of my favorite portrait mods, that make the characters look younger (in my opinion):
Kal's Marriage Candidate Portraits - https://www.nexusmods.com/stardewvalley/mods/2346
Bachelor and Bachelorettes - https://www.nexusmods.com/stardewvalley/mods/59

Installation:
 - Backup old C:\Program Files (x86)\Steam\steamapps\common\Stardew Valley\Content\Characters\Alex.xnb file (or just backup SDV as a whole)
 - Drag archive to StardewValley directory
 - Extract and replace Alex.xnb

Uninstallation:
 - Replace C:\Program Files (x86)\Steam\steamapps\common\Stardew Valley\Content\Characters\Alex.xnb with the backup created in step 1 of Installation.

In the unlikely event that other people also want characters we aren't marrying to be cuter, let me know if you'd want any other sprites done like this :)