Fellow DMs, has anyone ever let a player train up a skill in a lull of adventuring, and have an attribute increase? How did you handle it? Examples as follows, and sorry for the wall of text

1. The rogue in the party thinks that being able to Smith his own tools is a really good idea, and for a month in between adventures, he becomes an apprentice blacksmith, working from dawn till dusk. Blacksmithing is pretty physically intensive, and as a result he gains a point in either STR or CON, or perhaps both.

2. The party was flanked in the last battle and barely managed to scrape out with their lives, so the warrior takes it upon himself to research battle strategy, and as a result, gains a point in WIS.

3. The party wizard is sick and tired with having a 5 in CON (Dice rolls, man) and in between adventures, took up jogging to hopefully increase their durability