Time flies in tennis. Every time I come to a tournament, I feel like I was just here yesterday. We start the year in Australia, head over to America, spend four months in Europe, then back to America, before finishing in Asia. Two months later, another new season begins.

The names in the draw change, although everything else is the same. Everything, except for one thing: You feel older.

Everyone feels older. But sometimes you just don't feel the year go by. Of course, you know time is passing when you look in the mirror. I definitely feel all the matches I've played, all the years I've been on Tour in my bones.

I turned pro when I was 16, and by the time I was 18, I was already in the top 30. Looking back on that time, I'm surprised at how I was playing without any pressure. I was just hitting. I would go on centre courts and it was no big deal. I think that's how I improved my ranking so fast in the beginning.

Now I know what my opponents must have felt like back then. I have to say, the younger players on Tour right now are dangerous.

These days, the teenagers are playing really experienced tennis. I remember when I used to play against the younger players, they were not that good. They were just hitting the ball with no plan. Everyone can hit forehands and backhands, but they weren't constructing points well, so you just didn't feel any pressure against them. You were in control of the points.

The level in women's tennis has really improved. Everything is tough from the first round. Sometimes you might play a wild card, but even then, they're very good. There are so many players at the same level. Just because someone is ranked No. 50, doesn't mean they're not playing like they're top 20.

That's what's changed, for sure. The first round or two at tournaments used to be much easier. You didn't have to play 100 per cent and you were winning in two sets. Today? Forget about it. If you're not playing your best, you can just go take a shower and call it a day.

We talk about it among ourselves. The kids are coming! I think the new generation of players are just better than earlier in my career. They really play smart.

But there's more pressure on younger players to succeed early. From a young age, they're already pushing to play tournaments and matches. They're sacrificing a lot but that means they're very good when they're 16 or 17.

Of course, that could mean they burn out when they are 22 or 25. Everyone has her own story.

When I was a junior, I played tournaments and went to school at the same time, and I went step by step. I had a pretty normal life, only unlike my friends I didn't have much time for myself.

When everyone else was doing something fun, I had to run to practice. But I wasn't at an academy practising like a robot, practising hours a day to be perfect. Of course I practised a lot, but I think with a good balance between practice and a normal life, everything was natural.

Even now, it's not like I'm playing more and more. It's the opposite. If you play a lot, you burn out, and you're done. My schedule is the most important thing. Sometimes you don't think about that in the beginning. Obviously when you're young, you can play everything and you're strong. You play every week, you play singles and doubles, and you're happy.

Now you see everything from a different perspective. I'm 28 now and I'm more towards the end of my career than the beginning.

I'm not going to play tennis like Serena Williams when I'm 36, I know that. I've been on Tour for so long. I haven't had any breaks. I've had a couple of surgeries but I always had those during the off-season and I'm always ready for the Majors. I've played 43 Grand Slams in a row.

My goal now is to maximise the time I have left on Tour, and that means being as efficient as possible in my schedule by making the most of my opportunities.