It's great to see more people out and about being active due to the warmer, well sunnier, weather. At my local playing fields kite flying is popular at the moment, the cricket nets are always busy and there are families and groups of friends kicking footballs around, people walking and others jogging.
If you have been sedantary during winter be careful not to go too hard too fast too soon- Sports Medicine Australia have a good article up on their website 'Spring into Exercise Safely' check it out (click on the link). Generally it's a good idea in the first couple of weeks to ease into your new activity and allow a full recovery day between each session to allow time for your body to adapt. All going well you can then apply the FITT principle:
Frequency - increase the number of sessions OR
Intensity - increase the level of effort (eg. walk to walk-jog, increase weight lifted) OR
Time - increase the amount of time for each session or increase the number of sets OR
Type - change the exercise (eg. pinned machines to free weights, jogging on the flat to jogging on hills)
To keep your training interesting and challenging apply the FITT principle every two weeks.