Here is a fairly simple way to make 5e a short rest based game given the assumption that there should be 2 short rests per adventuring day.
First, convert spell slots into spell points. Then, have classes only get 1/3 the total amount of spell points they otherwise would. Now, most spellcasters will have roughly the same number of spells per day, but will function on short rest recovery. The spellcasters gain flexibility by the conversion to spell points but lose out on nova capability.
For daily class abilities like the Barbarian rage, just make the ability a per short rest ability with half as many uses (rounded down). Such abilities will receive a boost in overall uptime (assuming you do make it to 2+ short rests per day), but lose out on nova capability.
Next up is a change to HP. In a game based around short rest recovery, mac HP should be lower, but total HP per day should be roughly the same. To implement this, we remove Con mod from HP per level and get rid of HD healing. To compensate for this, all PCs get an amount of Stamina points equal to 3 + their Constitution modifier. During a short rest, a player can choose to spend stamina to regain HP equal to 25% of their maximum HP per stamina point spent. At the end of a short rest, a player regains 1 spent stamina point and at the end of a long rest a player regains all spent stamina points. If you want, stamina can also be spent for heroic effort to retool a failed attack roll, saving throw, or ability check.
The reduction of classes nova potential has an unexpected benefit for the game as it reduces the effectiveness of the 5 minute work day.