You need to realize that initiative (what you call "tempo") is only one of many factors that determine the evaluation of a position ("Who is better?") and consequently determine the best move (as you don't want to end up in a worse position after the move).
While playing aggressive attacking chess all the time might work against lower rated players; who are not that good at spotting tactics, at defending or who might be more easily intimidated by a piece sacrifice; if you play in the same style against stronger opponents you will find that more often than not your initiative is not all that sound. Indeed most won games at higher level are not resulting from directly checkmating the king in an attack, but from converting a tiny positional or material advantage at move 62 in an endgame.
I agree that playing like Morphy is more fun than positionally outplaying the opponent, but if you want to become a stronger chess player it is essential to broaden your horizon and not focus on initiative only.
I would recommend to start with evaluating a position (from your games or grandmaster games). In order to do so, ask yourself the following questions and do this for both sides (black/white)
- Are any pieces attacked?
- Are there obvious tactics available?
- Which pieces are well placed (lots of space to move around and attack something) and which not (little space to move and don't attack anything)?
- Is the king safe? Typically with many pieces on the board you want it behind pawns on either side after castling.
- Are there any weaknesses in the position such as isolated pawns, pinned pieces...?
- Who owns the center?
- Are there open or half-open files which are occupied or can be occupied by rooks?
- Is the position open or rather closed? Who would benefit from changing it?
As you see, I did not put "Who has the initiative?" here, because in my view, the initiative is made up of several factors like more piece activity, occupation of open files, etc
Based on the outcome of this evaluation you should come up with a plan. The difficult part is how to weigh the different factors, i.e., "Is a better piece activity worth a pawn sacrifice?" Or, "I am up a rook, but my king is under attack, will I survive?) Doing this correctly requires lots of experience. However usually, in most normal positions, dealing with attacked pieces (if you lose/win material) and keeping a reasonably safe king position are the main priorities and should get the most weight, before you think of anything else.
You don't need to go crazy with this evaluation, but keeping in mind that there are more factors than initiative is a good start. You could pay attention to one point at a time to get used to it.
Also IMO, at a level of 1400-1500 studying tactics will give you a lot more benefit than thinking of positional details.
